If this is a standard Red Hat Linux 9, then the correct path is /usr/bin/perl and your script should start with:

#!/usr/bin/perl.

If in doubt, type this command at the shell prompt, it will tell you where the perl executable is found:

which perl

As a side note, "Perl" is the language, "perl" is the program used to run Perl programs, but there is no such thing as "PERL". Please check the FAQ here.