How to resign when my opponent is not at the board? This happened to me yesterday.  It was unreasonable for me to play on, so I was going to resign but my opponent was not at the board.  They probably left the board to watch another game, waiting for my next move.

Question:  What is the correct way to resign if my opponent is not at the board?

I stopped the clock, wrote 1-0 on my scoresheet (I was black), and started resetting the pieces.  But this doesn't strike me as an officially correct thing to do.
I agree with Cleveland that what you did is probably sufficient. One other thing you can always do if you can't find the opponent and are concerned that you might be seen as doing something suspicious is to call the arbiter and announce your resignation to them.