This variant logic symbol ¬p is not listed in the Nemeth Code. The transcriber should devise a symbol that is in keeping with usage. In this case, I suggest a 2-cell "dot 4" symbol since the more common symbol of ~p (tilde p) is a dot-4 symbol. Note that, listed in Appendix B of the Nemeth Code, there are 71 symbols beginning with a dot 4 so choose your symbol carefully since you cannot use one which already has a meaning. I suggest (4, 1345) -- dot 4 "n" for "not" -- explained in a transcriber's note. Wikipedia says "No matter how it is notated or symbolized, the negation ¬p can be read as "it is not the case that p", "not that p", or usually more simply (though not grammatically) as "not p"."
If a reader has experience with this symbol and has come up with a different solution, please write. Thank you.