"Skilled Outrider" isn't a standard Magic keyword or ability—it's most likely a creature card name rather than a mechanic. If you're referring to a specific card, I'd need the exact text to explain it accurately, since card names don't carry inherent rules meaning the way keywords like flying, trample, or deathtouch do.
If you encountered this on a card, check the card's actual rules text (its abilities printed below the name and type line) for the keywords or triggered/activated abilities that govern how it plays. Those are what matter mechanically.
If you meant a different keyword—or can share the card's full Oracle text—I'm happy to break down exactly what it does, the common rules misunderstandings, and its relevance in Commander.