Just remove the "XMLFILE=YOUR RSS FEED URL" part. Then it will use the random feed that you configured in the rss2html.php
Like that:
<?php include'URL OF RSS2HTML FILE?TEMPLATE=URL OF TEMPLATE/sample-template.html&MAXITEMS=20'; ?>
Or you can leave the rss2html.php as it is by default and do the randomization in your index.php file. In that case you should write in your index.php:
PHP Code:
<?php
$myfeeds[]='url_of_the_feed_1';
$myfeeds[]='url_of_the_feed_2';
$myfeeds[]='url_of_the_feed_3';
$myfeeds[]='url_of_the_feed_4';
$myfeeds[]='url_of_the_feed_5';
$myfeeds[]='url_of_the_feed_6';
$myfeeds[]='url_of_the_feed_7';
$myfeeds[]='url_of_the_feed_8';
$myfeeds[]='url_of_the_feed_9';
$myfeeds[]='url_of_the_feed_10';
$XMLfilename = rand(0,sizeof($myfeeds)-1);
include 'URL OF RSS2HTML FILE?XMLFILE='.$XMLfilename.'&TEMPLATE=URL OF TEMPLATE/sample-template.html&MAXITEMS=20';
?>