...(snip)
$rss_out_file = "/home/foo/bar/public_html/RSS_feed.xml";

(A load of stuff to query our database and write the rows to
 an array of arrays)

open RSSFILE, ">$rss_out_file" or die "Couldn't open RSS feed file: $!";
print RSSFILE '<?xml version="1.0" encoding="UTF-8" ?>
<rss version="2.0">
<channel>
<title>RSS feed</title>
<link>http://(server IP address)/</link>
<description>blah blah blah</description>';

foreach $n(@RSStable)
{
print RSSFILE '<item><title>'.$$n[0].'</title><link>'.$$n[1].'</link><description>'.$$n[2].'</description></item>';
}

print RSSFILE '</channel></rss>';
close RSSFILE;