WS-Referral is pretty much only used if you are building your own SOAP Router. WS-Referral identifies the interface to a SOAP router not the actual wire protocol for routing; that is taken care of by WS-Routing.

As stated by the specification:

"Web Services Referral Protocol (WS-Referral) is a SOAP-based [10][11], stateless protocol for inserting, deleting, and querying routing entries in a SOAP router. A SOAP router is a SOAP node that exposes SOAP message relaying as a Web service, either as a standalone service or in combination with other services."