It would depend on the exact requirements. Armins solution seems solid to me, but a different approach would be to use one of the function modules that allow to add a day to a given date.
Put that in a do..enddo or while..endwhile and you can easily append these dates into an internal table until your required date is met.
The advantage would be that you can use the function modules that check the factory calendar and add only the working days to the internal table.