Capability Reqests authorization

As I understand it, you can give a user an "entitlement key" to be sent as part of a capability request. Such a key would have been generated previously by the back-end server and distributed to qualified customers, and then used in validating the capability request.

I am confused as to how to include the key in the C.R.; should I put it in a FlxCapabilityRequestAddRightsId call, or a FlxCapabilityRequestAddIncludeVendorDictionaryKey? Or have I overlooked the proper call?

Thanks.

/dps