This would have been a good situation to call "on your left" for...
I'm pretty liberal about that when it comes to biking and skating. Although, some people are hopeless. I was biking on a MUP the other day, and ahead of me was a lady who was walking as far right as could be. I didn't want to scare her by rushing by unexpectedly, so I called out "on your left to her." She immediately side stepped (jumped) to the left in front of me and i had to slam on my only working brake and went off the path fishtailing like a moron to avoid collision. Then she had the gall to try and yell at me. Cussing works good in such situations.