There seems to be an availability problem with potassium sulfite outside the US,where it is at Photoformulary.com.I only checked the UK and could only find the metabisulfite from retrophotographic.com ,no sulfite.
It may be that the version given by Bill Troop in FDC ,which uses metabisulfite,is the only viable Rodinal substitute based on potassium that can be made in some parts of the world.