This FAQ further describes the requirements and steps to create multiple HTTPS domains as HTTPS reverse proxy.
After the first HTTPS keyring is assigned to an HTTPS Reverse Proxy service on the ProxySG or Advanced Secure Gateway (ASG), and working successfully, you will be required to create another HTTPS Reverse Proxy Service on the ProxySG or ASG in order to differentiate it from the first one.
Either a different IP address (or VIP) is required, or a different destination port, which in this case might be port 443 or 444.
With each additional backend HTTPS server host, you are required to create additional VIPs and Keyrings on the proxy.
From the Management Console, select Configuration > Network > Advanced > VIPs
Note: VIP must be routable within the same subnet of the physical IP of the proxy
This enables the proxy to intercept the respective traffic and forward it to the correct HTTPS server host.
For detailed instructions see Reverse Proxy with SSL