Returning Stock to a Vendor on a Sales Order

Hi All

The Sales Order area is not my strength so apologies for a seemingly simple question.

We have approx 5000 materials (unrestricted stock) in a warehouse that we want to return to the various vendors for a credit. The Vendors have agreed a cost for the materials that are being returned.

How can I raise a sales order to show materials being returned to vendor and a subsequent credit for the sales order value being received from the vendor?

I wish to show traceability of the materials being returned to the vendors.

Thanks is advance

Darren