In the event that the pedestrian does not move, I slow down (multi user path) and say, "I'm behind you", then they'll turn, see me and move aside. I don't say "On your left" because sometime they will move left. Yesterday I rang my bell a few times, came behind person and said, " I'm behind you". She looked and said "Oh", then I said, "I wasn't sure if you heard my bell". She said "I heard it but didn't know where it was coming from". That seemed odd to me, because if I heard a noise I'd look around to see what it was. Oh well.
Some pedestrians on multiuser path seem upset by having to slightly move over for a second. I always say "Thank you" regardless of how they respond. I figure if being asked to share a travel way gets someone upset, they must have a pretty cr*ppy life to begin with.