Alright after watching episode 6.4 I am convinced that RJ is Ray Haffner. All of the clues fit too perfectly. Rosalind Harker's description matches Haffner- He has average height, straight short hair and is around the age of RJ (late 30s, early 40s). Then there are all of the clues that are associated with Lisbon.
The only reason RJ lets Lisbon go in 6.1 is because he either has a thing for her or is in love with her. We know that Haffner offered Lisbon to leave the CBI and join his own private security agency. This is because he cares about her and doesn't want her to get hurt. RJ only has a problem with PJ, not Lisbon. Also, when RJ calls PJ at the end of 6.1 he calls Lisbon "Teresa", and out of the seven suspects on the list Haffner is the only one that calls Lisbon by her first name, "Teresa".
Then there is the clue with "He is Man". If you put that together you get "Heisman", and we know that Haffner played college football and that there is some sort of trophy in his office. Also, in the season 2 finale RJ tells PJ "Roll Tide", which is the slogan for the Alabama Crimson Tide football team.
As far as the other suspects go, we are down to five. Partridge and Kirkland are dead. DEAD. They did not fake their own deaths, that would just be poor writing. Bret Stiles is too old to be RJ and I believe that Sheriff McAllister is not a big enough character to be RJ. Reede Smith doesn't fit the description provided by Rosalind Harker as he is too fat (and you know it). That leaves Ray Haffner.
Also, check out these two clips. Haffner and RJ walk almost exactly alike, this can't be a coincidence.
http://i.imgflip.com/4a7bq.gif
http://i.imgflip.com/4a7e2.gif
The clues make too much sense, RJ is Ray Haffner.
