I doubt it is FS if the Obverse looks the way it does with the circulation wear. But he might be reffering also to the Designer initials FS.. Strange thread
Here's what I think happened: The OP has heard something about FS (full steps) nickels being worth more than nickels without them, and has confused FS (full steps) with the designers initials (also FS) and thinks that this is "rare." If I am correct, I should explain that the FS (Felix Schlag) initials were on the observe of Jefferson nickels from 1966-2004, which means that this is a completely normal, circulated nickel. Also, the poll is optional.