Which transaction code is used to record the return of items back to the source of supply?

The transaction code RTL is specifically designed for recording the return of items back to the source of supply. This code is integral in logistics as it signifies that items previously received are being sent back, ensuring accurate inventory management and accountability. The use of this code helps to maintain precise records of items that are returned, allowing for adjustments in stock levels and facilitating the tracking of returned inventory.

In a logistics context, returning items can occur due to various reasons, such as defects, excess stock, or shipping errors, and tracking these returns accurately prevents potential discrepancies in inventory. The RTL transaction thus plays a crucial role in efficient supply chain management and maintains the integrity of inventory records.

Other transaction codes provided in the choices are utilized for different logistics functions and do not specifically pertain to the return process, which is why they are not appropriate for this particular action.