Dear Aurelien,
Fuji makes two types of peel apart type instant films.
One is 4 X 5 inch size, another is smaller 8.5 X 10.8 cm size.
What I understand Fuji B&W instant are FP-100B, FP-400B, FP-3000B for 8.5 X 10.8 cm size and these can be used with the RBSD.
(I don't have the original RB67 but the above Fuji instant should be compatible with the Polaloid one)
The FP-100B45, FP-500B45, FP-3000B45 are 4 X 5 size and cannot be used with the RB.
Indeed I have a RB67SD with two Mamiya genuine RBSD Polaloid backs which is actually made by Polaloid UK and modified in Japan and the above films are compatible with the Fuji instant (the manual for the Mamiya genuine Pola backs also stipulates that one can use Fuji instant).
For instant film (I only use color instant film Fuji FP-100C), I only use Fuji instant film with my RB67SD.
regards,