How do I keep the POV from switching?
There is no rule against changing the narrative POV, but there are some caveats when doing so.
The modern convention is to stay with one character's POV during a chapter or scene. (Scene breaks are indicated by inserting a blank line. That is to say, if you're double-spacing your manuscript, insert an extra double-space.) Be aware that including too many POV characters can be harmful to a reader's attention span; also, switching too often between POVs (called "head hopping") might cause reader melt-down. So, you'd be safe to let Rolfs and the fox narrate as you see fit.
(You can, of course, employ the omniscient POV, in which the narrator--unseen and above it all--narrates for Rolfs and the fox at will. Caution, though, for this POV style is considered by some to be outdated.)