To make TF-3 I order ammonium thiosulfate in a 60% solution and it smells pretty bad, but stock solution Kodak Rapid Selenium Toner (KRST) smells so heinous it'll snap your head back, so I figure it must be richer than 50% ammonium thiosulfate...otherwise known as rapid fix. Gasps of Horror!
jstraw...giving advice on such little information (what paper, what dilution, etc, etc, etc.) the only thing I would suggest is going with a two bath fix.
Check with Photographers Formulary for how many times, and for how many square inches of paper the first fix can be used before it's discarded, and then how many times the second fix can become the first fix before you have to mix up a completely new first and second fix.
If that last paragraph is the least bit confusing, check with the Formulary and all should be explained. (Waaaay too technical for me).