Awesome cameras. I found a 100ft rool of Single Perf NEGATIVE 16mm HP-5 and will use that until it is gone. From what I can tell, they discontinued that film.
Many years ago I used REVERSAL 16mm film. I was still able to make good prints by developing it as a negative, but not ideal.
Which camera do you have. You probably already know the early ones had a small frame, just a little bigger than Minox, because it avoided the double row of perforations. The later cameras had a much bigger frame, but you need the "Super-16" or "Single Perforation" film to take advantage of it.
I used to cut 16mm strips of T-max, but stopped once I got the 16mm HP-5.
You probably also know that if you take the film out of 'Kodak pocket instimatic' canisters, it was pre-printed with frame edges by our friends in yellow.
I use Prep Film for movie reversal processing, but don't recall them selling film. I have obtained Movie film from International Film. On last visit it looks like he just has Reversal film with double perforations which would not be ideal.
http://members.aol.com/Super8mm/JohnSchwind.html
Anyway, save those plastic film holders!
For processing, the Jobo 16mm reels work great.
Film for Minolta 16 
Linear Mode
