In an RDL, unlike a regular deadlift, you want to keep your knees relatively straight. (A soft bend is okay.) Bend at the hips until you feel a stretch in your hamstrings, and then stand back up.

The RDL also fires up more of your hamstrings than ... Lower until you feel a stretch in your hamstrings, don't bend your knees any further or round your back. Drive your hips forward to return ...