I recently bought a Certotrop (Certo bee bee) with a Rada roll film back.
The back is fitted with masks for 6x4.5, 6x6 and 6x9. These masks are fixed and non removable.

I'm having a lot of trouble loading film.
The smallest format being easiest and the 6x9 is possible, but the film is so tight that it is ripped and torn.

Any tips or hints for easy loading?