Any gold toner that works for kallitype and/or vandyke and/or albumen and/or salt prints is useable I think. I much prefer gold-thiourea for toning iron-silver prints...
Look for Sandy's (King) kallitype article @ unblinkingeye.com, also Wynn White's vandyke article at the same website. Also, I think Chicago Albumen Works had some info online, plus search for Reilly book on albument and salt printing. (Google and you'll find all of the above...)
Regards,
Loris.