E.U.regulations now require that the constituents of virtually every product must be itemised on the packaging - in descending order of proportions, although actual percentages apparently don't need to be disclosed (except in the case of comestibles, maybe?). These regulations may not apply outside the E.U., perhaps.
I'm fairly sure that tallow is the overwhelmingly predominant constituent of 'Proofide', and the various oils, waxes, etc. are no more than 'trace elements'. Any sort of oil, in anything more than miniscule quantity, is a sure way to ruin any suspension-type leather saddle and the use of neatsfoot, or suchlike, should be avoided if you wish to enjoy the various benefits to be derived from the use of these seats.
So far as the use of 'Proofide' is concerned, a light dressing two or three times a year is generally sufficient - on the top, never underneath. Heating the stuff is not a good idea - just wipe it on with your finger, leave for a reasonable time and then polish-off any residue.