the mount simply slides on the rail's dovetail untill it stops moving forward and contacts against the travel stop that is built into the rail.
the swing clamp is rotated approximately 180° to lock the mount on the rail.
the locking pressure may require adjustment as most of the rails vary in size. odds are, your locking pressure will be either too loose or too tight as it was delivered from the factory.
all the mounts, while varying slightly in there construction details, operate on the same principle.
they 'pinch' or sqweeze against the rail when tightened by rotating the lever.
consider the lever as a screw...and that lever/screw has a 'nut' of some sort on the bottom.
to add clamping tension, the 'nut' must be tightened up a little on the lever/screw.
to reduce clamping pressure, the 'nut' must be backed off (uscrewed from the lever's threads) a bit.
on some mounts, the nut is just that...a plain, simple hex nut (usually of the self-locking variety).
on other mounts, the 'nut' is a hook shaped piece of cadmium plated steel that is captured by a retainer plate. the retainer plate must be slide/pryed out of place before the 'nut' can be loosened or tightened.
i'll see if i can dig up tantal's adjustment instructions and post the link here.
tantal.kalashnikov.guns.ru/pso/clamp_adjustments.htm