ok, what are you trying to add, modify, or delete?
Look in /etc/e-smith/templates/etc/proftpd.conf/ for the files that are used to create the file /etc/proftpd.conf.
The short lesson:
If you want to add or modify something in proftpd, create the directory path /etc/e-smith/templates-custom/etc/proftpd.conf/. Add a file (numbered corresponding to where you want it placed in the file /etc/proftpd.conf) to this directory. Expand the template with the command /sbin/e-smith/expand-template /etc/proftpd.conf and then restart the proftpd daemon with the command /etc/rc.d/init.d/proftpd restart.
That should be it.
HTH