RDC stands for Resource Direct Cost. It is the hourly cost of an employee. Contractors are the most likely resources to have an RDC that changes based on the work they are doing.On project X they are paid differently than on Project Y. In order for your historical project profitability and margins to calculate correctly, this RDC must be as accurate as possible. This help article shows you some of the ways organizations choose to handle multiple RDC rates in Projector, the advantages of those choices, and the disadvantages of those choices.
Role RDC Rate Overrides
For each Role on a project you can specify an explicit RDC rate.
Downsides - you must remember to enter the RDC overrides on each role.
A vendor invoice is entered into Projector for goods or services rendered. Each contractor will submit an invoice for your hours which you will enter into Projector. The contractor also submits their time, but their RDC is set to zero so they do not 'cost' anything. In essence you transfer the cost of the contractor from the time side of the equation to the cost side of the equation. Each contractor should have their RDC set to $0 so you do not double count their cost - once for time entered and again when they submit their invoice.
Downsides - If you wanted to be able to use bookings to forecast profitability, the zero RDC hours will have no financial meaning in your reports. One way to address this would be to setup a cost plan and manually synchronize this to your contractor's scheduled hours.