Appeal a turn toward second.

[Paul L]

Having now read and studied this thread, if faced with the OP, I would give a quick, waist-level safe mechanic, and maybe say "safe". Some response to an apparent appeal is called for, although not required. Sort of like the 'that's-nothing' quick safe mechanic used when a possible interference or obstruction occurs that is neither. I think saying "improper appeal' in this instance would be slightly coaching.

AltUmpSteve got it right in post #14. I am surprised to learn that softball (Fed and ASA, at least) considers this an appeal play. I would have thought it would be a garden-variety tag-off-the-base play (8-6-2), the BR having lost the overrun protection by not returning directly to first base, a la 8-8-9. (Baseball treats it that way for attempts to advance to second after overrunning first; OBR 7.08(j), Fed 8-4-2-p)

For instance, if F3 somehow accidentally tagged BR off the base, I would still have an out. Right?