This will work for the recent versions of FreeBSD (you didn't say for
which version do you need it).
you need to make that script react for "start" and "stop" commands at
I just symlinked my sh script to /usr/local/etc/rc.d/ and it works
quite well without even touching rc.conf.
If your script dosn't have need of any information or configuration
from outside, then you don't need to put anything in /etc/rc.conf.
But, it is available if you need it.
As for start and stop, the system will pass start on a bootup and
stop on a shutdown. It is appropriate to check at least for start
in your script and only startup if it is set so you don't try to start
it at shutdown. But, if there is something you would like to do
at shutdown, then also make a section of the script for shutdown and
then check for 'stop' and run that part when it is present and 'start'
is not present. If both are set, then it is a bad error somewhere.