Clamping down your action ...
The RC2 Adapter plate screws down with a 3/8 thread, so you may new an enlarger insert to cope with your standard 1/4x20 tripod bolt. I do believe the adapters usually come with the insert, but they are easily gotten (purchased) from the camera store where you get these devices.
The Manfrotto pan-tilt head has the RC2 clamp built right into it.
The Manfrotto 488 Ball-head also has the clamp bulit into it.
The Manfrotto Grip-ball Head also has the clamp bulit into it.
The standard RC2 adapter does not allow any turning, as it is usually tightly screwed down on whatever it is you are mounting it to. In the case of my illustration ... it is a SLIK mini-tripod.
I bought several plates (which screw into the lens mounts, flash feet, camera bases and vertical grips. Each one has its place and I rarely remove them. If you do not do this, it kind of reduces the convenience factor ... and there is also a chance you could forget that plate on a lens you left at home. :eek: :o