header('Pragma: no-cache');
header('Content-Type: text/xml');
print '<?xml version="1.0" encoding="UTF-8"?>';
print '<!-- generator="pashtetrukaminah" -->';
print '<rss version="2.0"';
print '   xmlns:content="http://purl.org/rss/1.0/modules/content/"';
print '   xmlns:wfw="http://wellformedweb.org/CommentAPI/"';
print '   xmlns:dc="http://purl.org/dc/elements/1.1/"';
print '   >';
print '<channel>';
print "<title>$BlogName</title>";
print "<link>$BlogUrl</link>";
print "<description>$BlogDesc</description>";
print "<language>en</language>";

и цикл по постам

print "<item>";
print "<title>".$title."</title>";
print "<link>".$link."</link>";
print "<description>".$desc."</description>";
$date = date("D, d M Y H:i:s ", $date+$TimeOffset);
print "<pubDate>".$date."</pubDate>";
print "</item>";