Help with installation and config, Missing file...

hi,
I recently installed postgresql-7.2.2 onto a Linux RH 8 system via an
RPM. I am currently attempting to configure PHP4 with it and am running
into an error involving pg. Here is the command I am running:

./php4dir/configure --with-mysql --with-pgsql=/usr/bin
--with-unixODBC=/usr --with-httpd=/var/ww --enable-track-vars

the error I get is as follows:

configure: error: Cannot find libpq-fe.h. Please specify correct
PostgreSQL installation path

Everything else works fine. It seems to be configuring nicely with
everything else. But this file is not on my system. Doing a find from
/ shows me nothing. I don't know how to fix this problem.

Any help out there?

TIA,
A.V.