Nikon Camera F3AF - Manual (Page 84)

To remove the finder, use your thumb and forefinger to siide the
finder release levers @ toward the back of the camera; then lift
the finder out. Before attaching another viewfinder, a focusing
screen must be installed (please refer to page 54). To attach the
new finder, position it above the camera with the nameplate
facing toward the front of the camera, and gently push the view­
finder down until it is fully seated in place. Make sure the finder
is attached securely.
Do not forget to remove the focusing screen from the body when
you reattach the AF Finder DX-1. If not, both the focusing screen
inside the camera body and the one built into the bottom of the
DX-1 might be damaged.