The only one PJ really wanted to be at the house when he gathered his list of suspects was Mr.Stiles, cause he is the only one who knows who RJ is, PJ wanted to se his reaction when he said

One of you is RJ.

Bret Stiles just laughed like

You don't know anything, you really don't have a clue , do you ?

PJ always says that body language gives you away if you are lying or hiding something, so I really dont think any in the room is RJ, but I can be wrong and most likely I am.

I had my money on Partridge, and Mr. Stiles being his dad, but after joining this forum and read all the theories about other suspect I find them plausible as well , so I'm really in the dark, now I just look forward to the big reveal, and hope we get the best confrontation we all deserve, regardless who play the part as RJ.