Last night's episode tried to paint Smith as RJ, however it's led me to a different suspect.
Michael Kirkland.
Bear with me here. They wouldn't introduce a twin this late into the season without a reason, it could have been any relative to be killed by RJ, yet they went with an identical twin, which suggests a plot reason.
We know Robert matched Rosalinds description, so being his twin, Michael would too. We know Rosalind said that RJ smelled of Earth and Pine, Michael owned a cabin in the woods, surrounded by pine trees, as last night's episode showed. We know from the girl in Red Rover that he's in his late 30's to mid 40's, Kevin Corrigan is 44, so it's the right age bracket. The description also points to Haffner, but i have no reason as to why he would smell of earth and pine.
So the physical evidence points to Michael, he's the correct age, yet we've never met him, so we don't know of his personal traits. Twins do typically share some traits, so lets assume that he's intelligent, manipulative and flustered under pressure (like Bob was in yesterday's episode). That now fits with Sophie the shrink's description of RJ.
It's going to be one of 3 men, Ray Haffner, Sheriff Tom McAllister or Michael Kirkland.
Kirkland is the best fit.