Can't assign a value for a relationship's property.

First, I created a VF named 'SPGW', which have the components of 'LoadBalancer 0' (type of 'tosca.nodes.LoadBalancer') and 'ObjectStorage 0' (type of 'tosca.nodes.ObjectStorage').

Second, I set up a relationship between 'LoadBalancer 0' and 'ObjectStorage 0' using relationship type 'tosca.relationships.RoutesTo'.

Third, I want to assign a value for the property of the 'tosca.relationships.RoutesTo' named 'credential'.

But, I can not find this function on the SDC view.