I don't have a theory about who RJ is, but I have a small theory about why it is NOT Bertram.

My personal opinion is that RJ WANTS PJ to suspect Bertram by throwing off obvious and fake clues:

1- In season 3 finale, the female accomplice of RJ first enters Bertram's room, why would she do that? why wouldn't she directly go to the intended room? It is to make PJ suspect Bertram

2- Let's say that RJ investigated all CBI people in order to better 'play' with PJ. And suppose that during his investigation he discovers that Bertram is a William Blake fan, nothing easier to him than to quote Blake, it would be the easiest and subtle way to direct all suspicions towards Bertram. If RJ was Bertram, I think he would be careful not to quote Blake

Did you grab any other clues? would love to know your opinion regarding this matter

Gale Bertrem may be on the list but i don't think he could be Red John.
Red John is a mastermind, he must be incredibally smart. He was able to basically browse Patricks mind. In the episode that showed the 'poker club' he kept losing and he couldn't even figure out why. He wasn't even able to figure out that that guy was calling his bluff! Do you really think a mastermind would lose at poker?

I think Brett partridge is rj because in the season 5 finale when the photo guy says I always wanted to work with a famous killer Brett whispered "hi" 

The main question coming to my mind about the show is; what kind of an ending will take place? Because we have seen many shows until this one and each of them had its specific plot, specific casting and a specific ending. Ending tells a lot I believe. Storyline is of course important but in a sector with tremendous competition like this one, ending means a lot. 

Some shows made it good, some not. But the audience have taken their part from enough disappointments. So, I believe that the producers must be taking some certain precautions about not to be classified within the bad-ending shows. Because the biggest disappointment I've ever witnessed was Lost. And the level of disappointment was so high that people talked about it for weeks or months. I think that incident has changed things for wise producers. Because you have 2 choices when making a show with a certain level of mystery :

1- you just take your place in the book of clichés and disappointments 
2- You do the undone and keep your name up there with the unique creators 

Especially in a show like Mentalist, you must be highly prepared to remain a cliché since the nature of story has an open invitation for it. So many similar stories / concepts were played out in the history. I mean it's not "the pope being revealed to be a muslim" kind of story. It's just a serial killer story with a clever rival seeking revenge. So everyone in this forum can write his/her own story over this plot. It's that kind of commonplace. 

At this point I am asking myself the question whether it can ONLY be a matter of money for Heller or he means to slap such an ending to our faces as if he's saying "Yeah? Ya never saw this coming right bitchas?!" Well if it's only about money, then the show will remain as a relatively nicer show in our memories but nothing special. Otherwise, it would be a masterpiece. I don't know Heller in person, so I have no idea what his plans are. But if the ending will be a unique one, then the preparation must also be the same way. And this for sure must be something more complicated than the list of 7 and other stuff.

Just sharing some ideas but nothing else...

We don't know at all if the list that Lorelei said in the video is the same as Jane's list. Brun Heller said that we can trust the list, and what if we can trust the Patrick's list?

I am in school and I have just realised something about Bob Kirkland. I think he is a good guy and trying to catch Red John. Only he is trying to catch Red John before Patrick Jane does.
Red John probably has done something to Kirkland which is why he is after Red John.

I also believe Bob Kirkland knwos exactly who Red John is...

Red John attempted to kill John Lennon but failed. Bob Kirkland knew that if John Lennon survives then he will tell Patrick Jane and the police everything about Red John and possibly who he is. So Kirkland had to kill John Lennon before he says anything....because Kirkland knows who Red John is and doesn't want anything else to find out.

So yeah, I think Kirkland is a good guy and is trying to find Red John too. I hope to see more from him in Season 6.