A knowlegeable commenter on another website recently warned against "pigeonholing" OL prospects before they have an opportunity for development in a college program. I certainly agree with that, but OTOH a player's frame is what it is. You can't teach it. If we were talking about DBs, sometimes it can be difficult early-on to tell whether a young player will develop into a CB or S, especially in the Stoops/White system that uses a nickel and a lot of zone doctrine.
But in the case of the OL, there are five different jobs that work in coordination, but each job is different. There is no golden rule that says a RG cannot be used as a RT if the team doesn't have a better alternative. Last year, Kenneth Horsey moved from LG to LT precisely because the team didn't have a better alternative. But there is the rub. Natural OGs can be used as OTs. Nobody will call the police. But the result might be a less effective, less competitive OL, especially in a spread or prostyle offense where pass blocking on the edge is a deal maker or deal breaker for offensive effectiveness. If you can't protect the pocket and keep the rush off your QB, then it just doesn't work. We sure learned that last year despite the fact that Horsey is a good football player. Horsey just isn't an SEC OT. He doesn't have that kind of frame or length. But he is a preseason all SEC OG. So let's think about that.
Regarding Selm, I have seen height listed anywhere from 6'3" to 6'5" and weight anywhere from 280-300#. As a fan of recruiting, this is a commonly encountered issue. Unless a prospect has been publicly measured without shoes at a credible combine, you just don't know. After much review of this, I believe Selm is 6'3". Can he play RT? Sure, why not? He is athletic and smart.
But let's ask these two questions. Is it best for the team if Selm is a RT? Is it best for Selm's development and career if he is a RT? Here, we have to acknowledge that we won't know the answer with certainty for another couple of years. IOW, the commenter on the other website is correct. All I can add is this. Selm doesn't have the build of a RT. Darian Kinnard had the build of a dominant SEC RT. If Horsey can play LT, then Selm can play RT. But if Stoops' program ever gets back to dominant BBW status, as we all hope, I am inclined to project Selm (and Lafontant and Johnson too) as an interior lineman. When the time comes, we will find out. I am glad Selm committed to our class. He is an intelligent, widely recruited player. But I expect an OT or two will get added to this class later.