So since Savitar's identity was not revealed tonight on the flash, but Killer Frost did find out who's under the armor, my prediction as the title of this post reads is that Ronnie Raymond is actually Savitar. Spoilers for Season 1 of The Flash So obviously at the end of the season 1 finale Eobard opened up warmwhole that allowed Barry to go back in time and save his mother, which he didn't do when he went back to the night she died, and when he returned a singularity opened up over central city and Barry closed it with the help of Firestorm causing Ronnie to die. So this is were my theory come into place when Ronnie got sucked into the singularity we never actually saw his body so by comic book rules, no body = not dead, Ronnie got throw back in time to an unknown date. While he was in the past he found the philosophers stone as he thought it would be a way to bring him back to the future. This then granted him super speed and he became Savitar. This is also why when he revealed himself to Killer Frost in tonight's episode she immediately trusted him without asking any questions as Ronnie would be the only person who she would trust that quickly.
That is just my guess as I think the show hasn't really given us any clues at all about Savitars identity, but let me know what you guys think do you agree or disagree. And by the kill of it we'll find out next week whinSagitar truly is.