Ritual Aptitude is a depreciated Classic advantage from GURPS Spirits that was woven into Magery, as "Fractional" Magery 0, in the Path and Books version of the 4e Ritual Magic system
Hellboy Sourcebook and Roleplaying Game allowed Clerical Investment to substitute for it to remove the -5 for casting some Path of Spirit rituals, but not for removing the skill cap of 12.
HB just called Ritual Aptitude 5 "Ritual Aptitude" like it called Magery 3 "Magery".
Also since this allowed casting without the Ritual Magic skill, the Path of Spirit skill could be selected without that prerequisite.