Well there should be a visible return edge on the mold of your armour kit.. but I think the only places that do not have returns are sides of the ab and kidney, chest and back. The sides of the bells (so the bottoms do have a return edge), bottoms of forearms (near wrist) and bottom of the greave (near the ankle) as well as the belt. Everything else should have a slight to moderate return edge depending on the make of armour and also comfort/personal preference. So ones that do have returns are all arm and leg pieces save bottoms of forearm and greave, bottom of shoulder bell, chest front, cod piece, back piece (also the tops of the chest and back pieces can have return edges, very slight ones but some people choose to remove for comfort), hand guards, sniper plate but not knee ammo box.
You could also just look at someones centurion application for example for close ups of pieces etc if you are still uncomfortable