There are three requiremenst for SSL.
RS 15.0 or later supports TLS version 1.0 or 2.0; it does not support SSL version 3.0.
SSL requires Replication Server version 12.5 and later. Earlier versions of Replication Server do not support SSL.
The Replication Server Administrator must generate and secure the server certificates and trusted root CA certificates as files outside Replication Server.