Calculate Due Date Based On Work Days

I found the netWorkDays function, however I don't think it applies to what I want to accomplish.

I want to track jobs with a due date of 7 business days after initiation.  So if a job (record) is begun (created) on 9/1, I want the system to automatically calculate the due date that comes 7 business days after 9/1.

Does anyone know how to accomplish this?