Use this formula; the stock solution has a very good shelf life (at least 3-4 months) and it works wonderfully with any of the iron-silver processes.
I use the same toner formula for lith and standard prints. I make up 200ml at a time and use just enough in a flat bottom tray to cover the print (surprisingly little). I then save the used toner in a separate bottle. It has a pretty good capacity. When it stops working (a few prints), I discard it and start with new.