I don't think I've seen posted rules to walk (or ride) to the right. But, I think everyone generally walks or rides to the right... except for the few who will walk wherever they please (or groups who use the whole path). People also tend to move right when being passed... except when they move left.

Very few "lane markings" here on MUPS.

We have several sawdust paths that are popular with joggers, and gets them away from bikes (not mandatory, but it helps). Walkers tend to stay on the paved areas. Beware of them coming from off the path onto the path without looking.