It's fiberglass, so repair like any minor fiberglass damage. Sand or grind away paint in that area, clean and fill with fiberglass body filler, then re-paint. If severe, you may have to bond reinforcing to the backside to give structural support.
Former owner of 2004 American Tradition and several other RVs
Home is in the Ocala Nat'l Forest near Ocala, FL
Summers in Black Mountain, NC