Oracle Order Management provides Return Materials Authorization (RMA) functionality within the Sales Orders window, where you can enter both standard and return order lines within the same order.

An order can have a mix of outbound (standard) and inbound (return) lines, as restricted by the order type definition. 
A return line is indicated by Line Type Category of return negative and highlighted item quantity and negative line total.

Return Line types can include flows like

Creating RMAs
There are three ways to create RMA's within Order Management.

• First, identify a sales order to be returned and query the order lines. After you have selected the sales order or order lines, use the Copy function in the Actions list to generate the return order or line by specifying an RMA line type.

• Second, reference a sales order, invoice, PO number or serial number of an item directly in the Return Reference field within the Line Items tab of the Sales Orders window.

• Lastly, for return without originating sales order line, manually enter return line information and choose the appropriate return line type in the Sales Orders window.

Workflow
Order Management comes with seeded Oracle Workflow processes. Review the seeded flows, activities and notifications to determine if the seeded data can meet your business needs. To successfully enter an RMA in OM, you can use the Generic - Order Flow Return with Approval and Line Flow - Return for Credit only.
With services, OM will use only the seeded "Return for Credit Only" workflow for returning service items when product items are returned

Transaction Types
Both order and line transaction types need to be setup in order to process an RMA.Credit order types have an order type category Return. An order with a Mixed order type category can contain both standard and return lines. Line level workflow processes are assigned based on the order type, line type, and item type combination. When you setup a return order type or mixed order type, you have the option to set a default return line type, so that the user doesn't have to manually choose the line type unless they want it to be different.

Master Items
You can create a return line only if an item is Returnable. Therefore, a standard, finished good item should be defined in Oracle Inventory with appropriately set attributes. The best way to create your items is to copy them from the Finished Good seeded template and set additional attributes as needed in the Master Item window

Return Reason Codes
You can set up your own reason codes in the Receivables QuickCodes window. Navigate to the Order Management responsibility and select the menu: Setup > Quickcodes > Receivables. The Oracle Receivables Lookup window will appear. Query the CREDIT_MEMO_REASON code from the query manager (Flashlight icon). View the existing codes or add a new code. These codes appear in the Return Reason list of values.