Rollei's Pistol Grip is very useful accessory when you photograph at eye level or with the Penta Prism, which is also one of the Rollei accessories.
Views from the front and the top show that the part of grip comes not right down from the rail part but at an angle. This is because there are two kinds of Pistol Grip and the one in the pictures is made for the right-hander.
About attaching it to the camera body.
Slide the round-shaped double-lock part at the camera bottom into the rail of Pistol Grip.