It is. If the tournament is not organized by FIDE, or a national chess federation, it won't affect your FIDE rating.
It will also not affect your FIDE rating if the tournament is not organised to the required standard (which is basically nonexistent for under-1800 rated players, and going all the way to the required presence of International Arbiters, metal detectors and blood tests for top level play)
has Adderall been shown to enhance performance or is this a preventative measure to protect player health?
what else do they check for? caffeine is probably helpful and not banned. LSD (microdosing)? Galantamine? If there are nootropics that can legitimately enhance high level chess play why aren't we using them on our top scientists and engineers?
It will also not affect your FIDE rating if the tournament is not organised to the required standard (which is basically nonexistent for under-1800 rated players, and going all the way to the required presence of International Arbiters, metal detectors and blood tests for top level play)