replaykit is not a server application. It does not listen on any port. It embeds an ADB client that talks to any ADB server.
Most replaykit commands allow you to talk to a non-standard-port ADB server, e.g.,
usage: appetizer trace record [-h] [--port PORT] [--host HOST]
[--device DEVICE]
trace_file
appetizer trace record: error: too few arguments
port, host here
The problem that replaykit might not work along with STF is because they both use minitouch to control the device. minitouch runs in as a daemon process on the device. Both need to control it.
I would like to run both stf and replaykit, can replaykit run on a separate port ex: 5038 adb start-server -P 5038