Tilde shortcut duplicates my key
I didn’t know that holding a key in OS X produced a list like that. Very useful!

Not a direct answer to your question, but may help you, is that if you type alt+e then o you will end up the the “ó” character. 

The alt+e combination gives you the acute diacritic mark, then you just enter the letter you want to put under it. So alt+e then e works to get “é” too. 

You can also do alt+e then shift+o to get “Ó”.