if it was me doing the work i would use something like this: http://www.levineautoparts.com/icing.html
or this: http://www.levineautoparts.com/spotlite.html
because i come from the bodyshop trades. but it would be pricey for a single use.
if the damage is deep i might go with one of the two part epoxy repairs that come in a double syringe at lowes or any hardware store.
if the damage is shallow just rough it up a little and use any name brand wood putty.
whatever you decide on plan on more than one coat and give the repair plenty of dry/cure time.
the links i posted are to a site that i have never bought from so use it as a reference only. even amazon should offer a similar product.