I bought a bottle of TF-4 from Monochrom in Germany. Maybe Silverprint carries it as well?
I have to admit that I don't support Formulary that much. I wanted to compare TF-4 with my own mix: TF-4 wins barely on speed, my own is a clear winner on smell. And I thought that was bad - I'd have to get a very much better ventilation system for my darkroom if I were to use TF-4 on a regular basis!