My dogs are raw fed, but I don't give them raw potato because it's one of those foods that the jury's out on. If you do an internet search you'll find plenty of information (or misinformation) ranging from toxic, to harmless in small quantities providing the peelings aren't green or sprouting.
Potatoes are a member of the Nightshade family, so the leaves and stems of the plants are a definite no, which is why I think peeling that's green or sprouting is also a no for feeding.
But although I choose not to feed it I wouldn't worry if either of mine scavenged an odd bit of peel that I'd dropped (providing it wasn't green or sprouting) because I don't think the occasional small amount would do them any harm.