How do you backstab in Bloodborne?

I can't seem to figure out how to backstab in Bloodborne, it doesn't seem to be like in the previous Souls games, Can someone give me a bit of insight on this?

From the Bloodborne Wiki (well, one of them) :

Backstabs in Bloodborne can be performed by holding R2 (charging up your heavy attack) and releasing it into the back of the enemy. The enemy will be briefly staggered, allowing you to position yourself directly behind it and press R1, performing the backstab.

This is a change form Souls games, where all that was needed was the R1 attack behind the enemy.

You also can chain backstabs, to do so just charge your R2 again as soon the previous backstab animation is over, by the time your target's standup-animation is done your second charged up R2 will hit and you are free to backstab again.