Yes, you can absolutely do this without damaging the Phantom application.
Phil is saying you can wax a ski that has had the Phantom treatment. I did that a few times this year. It didn't affect the phantom at all.
I had mostly good results doing it, the wax caused the one bad result.
The issue with most wax is its temp. range. I used wax on top of Phantom for a race I did and it worked fine in that temp.I would say I got a little better glide than just with the Phantom. Kind of hard to tell, really. A week later, in very different temperatures, the wax was sticky and was driving me crazy. I brushed it off as much as possible and used the Swix citrus cleaner. This got me back to just Phantom, and I was happy with my glide again.
Just last weekend, in warm spring conditions, I used a Phantomed ski for a few runs and it did well. For kicks, I put some Dominator Butter high fluro rub on wax on the ski. and worked it in with a cork. It worked even better in the really wet mashed potato snow. I would say about 20% better glide. Less sticky when walking in the lift line, too. That is the noticeable thing about Phantom, it doesn't feel super slick in the lift line, like a fresh wax job does. The Butter wears off before the end of the day, so I didn't have to clean it off for future use.
I am so used to Phantom working pretty good in all conditions, I forgot how bad wax works in the wrong conditions. I don't wax much anymore, so not a big deal to me.