how to insert client IP address in tcp profile for FTP connections

There is no such thing as an "X-forwarded-for" header in FTP. The only chance to retain the original client IP on the server side connection is not using SNAT.

If you need to only log the original client IP (e.g. for accounting or so), you could generate a syslog entry on the f5 that contains the original client IP and forward this to your centralized management using normal syslog mechanisms.