Have been testing this newly released functionality (as a 'super' user in Cronus GB Dynamics NAV 10.0 (18431)). It works, after a return receipt number series has been set up on the Sales & Receivables setup page.
Two issues. Firstly the return reason field on the return line does not work. There are no return reasons already set up and it is not possible to add new ones - clicking the '+ new' link on the 'return reasons' page does not do anything. This needs to be fixed because reason codes will be needed for Sales Order Returns.
Secondly, a field for 'Responsibility Centre' shows on the Sales Return Order header (when 'show more' is selected). D365FO Business Edition does not have responsibility centre functionality (sadly) so not clear why this is showing.