Wouldn't that be toning them Yellow to yellow-orange to get cyan/blue print with RA-4? But maybe you are after a yellow/orange print.
I make up a blue toner for our students -- pretty cheap and easy. Not considered "archival" is the only problem. It is made of Ferric ammonium citrate, Oxalic acid and Potassiun ferricyanide. Nothing expensive -- pretty much what one makes cyanotypes with. The formula is from an old Kodak book of photographic formulas. I'll look it up and post it if you are interested.
PS...it is just a silmple solution -- soak the print in it, then wash until the whites clear. Definitely gets the shadows blue...no black shadows.