So, I'm looking at the Skald. The Skald gets a limited number of perform skills (not all, like the Bard)...specifically, it does NOT get Perform(comedy).
Now, I see nothing in the Rage Song that says I couldn't use Perform(comedy) to do my Rage Song, right? From what I can tell, the only thing I would lose is Versatile Performance...or am I missing something?
Of the five Raging Songs--Inspired Rage, Song of Marching, Song of Strength, Dirge of Doom, and Song of the Fallen--none use any Perform skill checks. Therefore, you cannot use Perform(comedy) nor any other Perform skill with Raging Song. Versatile Performance is the only mechanical issue.
From that logic, the Bard doesn't need Perform to Inspire Courage either. Meanwhile, both mention it (in a nonmechanical way) in the beginning of the description for Raging Song/Bardic Performance.
This was a deliberate design decision that the developers discussed back when Pathfinder was in play testing. Basically, you enact some sort of performance while you are doing Inspire Courage, but there is no need to actually roll the skill or even specify exactly what you do beyond whether it has audio or visual components.