There should normally not be any withholding on 1099-DIV unless the taxpayer is subject to backup withholding.  Furthermore, 1042-S instead of 1099-DIV should be issued to NRAs who have a W-8BEN on file with the withholding agent.

For 1042-S, you'd make the input under Miscellaneous Forms > Foreign Withholding (RRB-1042S, 1042-S, SSA-1042S).