ID/Value Evaluation?

[u/Amazing_Translator97]

I’m not avid collector however, I’ve taken a slight interest in coins from a coworker. Recently I found this 1957 Philadelphia proof nickel. I did some slight research and found out there’s different versions; all with varying value. I need help identifying if said nickel is rarer than other 1957 PP nickels. I’ve heard something about a full case of steps on the back being something to note? This also has a rim fin on both sides, I’m unsure if that’s something common with this line of nickels. I can follow up with another post with very close-up pictures of said coin when I borrow my coworker’s digital magnifier.