Cooderm
Never flown a katana but have a goodly number of hours on Pipers (PA 24 and PA 32) both with VP.
Basically you need to set the RPM with the throttle and then the pitch with the pitch knob. There will be basic numbers for take off/climb and whilst in the cruise. You need to monitor it during the climb as it will need adjustment as altitude changes.
Main thing to look out for is that it is easy to over-rev the engine in the descent if you forget the pitch control.
Procedures may vary with aircraft type, but, once you get used to the extra step, it’s quite straight forward.
Cheers, B-E