I've played the Game through atleast 4 times even if it has been awhile since i last played it i never have seen hints or clues to R=U theory. I suppose any theory that could be even considored would be that Ultimecia could be a dessendant of Rinoa. As Riona is the only Sorceress left at the end of the game and Ultimecia is generations after Riona, so perhaps she is her childerns childrens child, you get the idea.