Try this. (back up your apache.conf first)
use pkg_info and pkg_delete to remove any instance of apache that you have on the machine. Now install the apache13 (or apache13-mod_ssl) from /usr/ports/www.
After you've installed either of those, just cd /usr/local/www/mod_php4; make install clean.
After the installation is complete, you should have a default installation of apache 1.3 that supports php. Just test it with a index.php file in /usr/local/www/data/ that has <? phpinfo(); ?> as the only line in it.
John