ilyazhito wroteIsn't that just a special case of "after a timeout"? If they are just dribbling out the clock, I don't do anything, just let the horn sound. If there is anything that looks like a shot attempt, I blow the whistle and either score the goal, blow the whistle and wave it off if it is late, or do nothing.
IAABO is very clear regarding whistles at the end of a period, and before a free throw after a timeout.
Whether we do it or not is another story for another time in another place.
2018-2019 IAABO Significant Manual Revisions
End of Quarter/Period Procedures. By rule, the game clock horn signals the end of the quarter/period unless there is a ball in flight on a try for goal. Officials should not sound the whistle to signify the end of the quarter/period unless they are ruling that the try was not released prior to the sounding of the horn.
Time Out Procedures: When a timeout is followed by a free throw, sound the whistle prior to administering the free throw.