Dead by Daylight

Heavy Burden

The achievement is fairly self explanatory although this game has a tendency of wording their achievements incorrectly, so buckle up Hunters, there's a bit of a read to come.

Simply down a Survivor and whilst carrying them to a Hook. (You don't need to get the Hook) Injury or Down another Survivor with a Survivor over your shoulder. It's a very situational and fairly luck based achievement.
There's no exact guarantee that you'll get a notch towards this every game but there's a few things that should help you in your quest to achieve this.

Obsession Perks:
Play With Your Food
Dying Light
Save The Best For Last

All are Perks for The Shape, they do occasionally appear on the weekly Shrine of Secrets and will cost you between 2,000 and 2,700 Shards but I'd definitely go for Save The Best For Last!
It gives a better penalty to all survivors permanently and is harsher than Thanataphobia. You'll see why I choose this later.

You'll want to look out for Groups joining your lobby. They'll work together and most likely will try to "block the Hook" to help their friend escape or prevent the last Hook for their friend.

Flashlights in lobbies. Now as much as any Killer hates them. They're going to try and flash you when you're picking their friend up. To avoid being Blinded, try to face any solid wall or narrow the gap when picking up a downed Survivor. They'll have to get closer and boom. You've got yourself a hit. They'll most likely try to make you swing for them whilst you're transporting to the Hook. Be patient, the less you swing. The less "interested" you seem in getting them so the bolder they usually get until you're at that Hook.
Listen to the footsteps, you can usually hear Survivors ready to help on standby running around the grass as you're picking up someone. Pretend to not hear them, don't look and I'm sure they'll be right behind you the entire way and just 180 swing. You'll scare the daylights out of them and get yourself a notch. Plus it'll wear down the timer of your Hooked victim a little more since their rescue is now delayed.

Important:
Now you are welcome to use any Killer and any Perks! It's about how YOU play the game. My only reasoning for STBFL is that after Groups see the same Killer and know what Perks they're going to be using. They're either going to quit the game or try to save their friends more from the known penalty to come.
Saying that. Please be wary that even though you'll have 1 Obsession per game. The other 3 Survivors including the Obsession may be running Boil Over (Kate Denson) or Decisive Strike (Laurie Strode)

As far as the wording of the achievement is. I believe you can only get a maximum of 4 notches a game as per individual Survivor comes. I'm not sure if you can hit the same Survivor in another game and still get a notch or if it is unique Gamertags that need to be hit.
I will confirm later and credit anyone if they happen to find out so!

Your other option is if a group joins the game, just message one of them before the game starts that you're going for a achievement, whichever one it is you're going for and let them know that the game is theirs.
You'll most likely get the group of notches towards it at the expense of losing the game. Which most players don't really care about though you will get the occasional one who'll cry through your inbox saying that you're cheating and farming Bloodpoints. Don't worry about them. You can just tunnel them the next time you see their tag if it makes them any happier...

Most groups and the community in general are usually very helpful and fun to mess around with in Ranked matches (there's a little more on that on my Feast For The Entity guide) don't break the bond of trust with that community by screwing over the Survivors after you've said that you'd let them go. They'll want to slam some Pallets on you, cleanse some Totems, Chase points and Geny's.
But for a couple of hits in exhange for a promised win is usually a no brainier. If you're going for this method. I'd also recommend turning on your Achievement Tracker to see if the notches are counting

(Would like to state that the criers aren't technically wrong, it is boosting and a complaint that can have action taken against you but in realistic circumstances. How many complaints/reports have you had as a Killer already with people complaining about how you played the game?)

TLDR:
It's a very luck and situational based achievement. When you have a Survivor on your shoulder. Play dumb or pretend you don't know where you're going or what you're doing. Survivors will get cocky and run in front of you. Hit them. There's your notch.
Only 4 notches can be obtained per game per individual Survivor. Playing against Groups will more likely have one or multiple players trying to block your hook whilst you're transporting a Survivor.

Hope this helps!

You will likely get this achievement organically as many survivors will body block hooks and take hits while you are carrying.
A fun way to get this quickly is run Mad Grit, Agitation and Iron Grasp. Mad Grit is a Legion perk that removes the cool down on missed attacks while carrying someone. Agitation is a trapper perk that lets you move faster while carrying. Iron Grasp gives you more time and control when carrying.
This build turns you into a blender while carrying survivors. Its pretty fun even when not going for this achievement.