Distribution to Participant who lives in Puerto Rico

[Vlad401k]

We have one participant in one of our plans who lives in Puerto Rico. He is a U.S. citizen.

How should his direct distribution be taxed.

1) Will the mandatory federal tax withholding still be 20%?

2) Will there be any mandatory "state" taxes upon distribution? If so, what would they be?

I tried to look up this information online, but there are very few sources. Has anyone had experience with this?