Taking full feather strokes, add a pause at the finish before the tap down. Blades should be rolled flat onto the water at the pause. Then rowers should tap down and bring their blades off the water as they begin the recovery, with enough clearance to square before the catch.
Progression
Move the pause to every other stroke, every three, and then go continuous. Ensure the technique is consistent between paused strokes and continuous strokes.
Note
If a blade comes off the water before the pause, that indicates handle heights were too low coming into the finish.