Correct Pullover Form

I just recently learned of this exercise and i was wondering if you do it with your back lying on a flat bench or not, on exrx.net/WeightExercises/PectoralSternal/DBPullover.html
it doesnt do this but ive seen it done while lying on a bench. Which is more effective?

Do it lying on a bench. You can put your whole body on the bench, which is what I would do. If you do it like the picture on the website you will probably get a little glute and ab activation to stabilize.