Resolution:
The connection between two RTservers is like any other TCP connection. The RTserver that initiates the connection acts like a client and the one that is listening and accepts the connection acts like a server.

In this general case the server process inside the firewall listens on a well known port (in the case of RTserver this port is specified in the RTserver conn_names option). The client outside the firewall requests a connection on the well-known port id. The server process (as part of the accept proces)  gets a random OS generated port number and creates the client's actual connection on that port (from inside the firewall to outside the firewall).
Smartsockets does nothing to alter or control this behaviour. If attempting to connect two RTservers on either side of a firewall and the firewall policy allows outgoing connections then the  RTserver on the outside should initiate a connection request to a RTserver on the inside. You will need have to open a port (default 5101) in your firewall so that an outside RTserver can initiate a connection request to one one inside.