PHP include code fail

Hello,

I try to get an php page into my .htm page. Therefor I use the plugin:
“runPHP”.

It goes about this php code:

<?php
include('rss.php');
?>

Now it says this:

Fatal error: Cannot redeclare get_link() (previously declared in /home/mkdesign/domains/design-links.nl/public_html/wp-includes/bookmark.php:93) in /home/mkdesign/domains/design-links.nl/public_html/rss.php on line 46

Anyone knows the problem?
I am sorry for my English, I am from the Netherlands.

Thanks!