good form ?

Is it considered bad form to force a draw through repetitive checking when it is obvious that the opponent would otherwise win ?

It's not bad form at all; It's part of the game.

Just don't rub it in, though... ;)

I only ask because the chess.com computer program seemed to think it OK

As long as the computer didn't rub it in...

Nah, Rees Mogg only plays tiddlywinks, usually with Ms. Sturgeon.

well, it is extremely unbritish. you should resign. taking a perpetual check is taking advantage of a sick loophole. chess is for tough guys, not wimps.

Of course you should take a perpetual draw if givin the opportunity when you're otherwise lost. I've sacrificed a piece for a perpetual before when I was losing. It was glorious!

It's called perpetual check and even top GM's do it... often even.  It's just part of the game.    

Computers would evaluate such positions as equal.  Cant get more objective than that. So why not?

Not bad form at all. It would be a tactical and strategic oversight to pass on the threefold repetition in such a position. I can assure that if the position was flipped anyone in that spot would force the draw in a heartbeat should they see it.

EscherehcsE's point is valid though. Just because you escaped a position you should have lost doesn't mean you're necessarily better. Maintain honor, a bit of humility, and learn from the game afterwards. The fact you landed in such a position indicates something went wrong somewhere in the game.