Every time Partridge goes, he says it's not Red John.  He obviously has a sick fascination with death, he's a creepy emo guy, a high pitched voice like Red John, and it was weird that he was there in this episode.  He almost seemed happy about it.

I also think it could be one of Jane's old acquaintances from his circus days.  Lorelai said they had shook hands, but it doesn't necessarily mean it was after Red John started killing.  It could have been someone he knew from his childhood, which would explain how Red John could have targeted his circus memory in the Season 5 finale.  I think it's possible it's not one of the seven suspects, but if so, probably most likely Partridge.

I think this rules out Kirkland as RJ.  RJ apparently knew all the suspects by the time of Lorelai's murder, which was several episodes before Kirkland broke into Jane's office.  (And what would be the need if he already knew the names on Jane's list?)