Yes, you will need some kind of keyer like a Winkey to key at the remote site.
We use the setup that you described when we do a Multi-op contest operation, and we need the log to be present at the remote site for all to use. If someone is doing a single-op effort remotely, we use N1MM on the control computer and send the keying out via the Remote Rig boxes. Then the log stays at the Control computer. Just depends on how you want to do it.
Dennis W1UE