The act of binding a particular client to a particular service and transport parameters is NOT part of this RPC protocol specification. This important and necessary function is left up to some higher-level software.
Implementors could think of the RPC protocol as the jump-subroutine instruction ("JSR") of a network; the loader (binder) makes JSR useful, and the loader itself uses JSR to accomplish its task. Likewise, the binding software makes RPC useful, possibly using RPC to accomplish this task.