You don't have to say check and most players usually don't. Saying checkmate is optional too.
OTB etiquette
I don't think you should say "check", it's not only annoying, but could be distracting too. When there is a checkmate your opponent will see it and resign, if it's taking too long ( though, I never had such situation ) maybe you can politely point out.
If they don't realize they are in check and they touch a piece that can't be moved, that's considered an illegal move and you can flag down the TD to get time taken off their clock.
Also on a side note, I witnessed a situation where a player was in check, didn't realize it, and moved a piece (his rook) to some random square. The opponent quickly got the TD, and announced he made an illegal move. However, becuase of the "touch rule", he had a legal move with his rook to block the check, but which just left it hanging. Unfortunately the rule was the rule and his rook was taken without mercy. Just something to think about: always look to see if you are in check.
Hello,
I recently started playing in organized over the board tournaments. I have a few questions regarding when you put a players king in check or mate.
When you put an opponents king in check, should you actual say anything? My thought is that it is pretty clear, so why say "check." Seems annoying to me. How about when you checkmate an opponent?
Thanks.
Momadu