RSS Generation

I am working on creating some RSS feeds on my website using PHP. I'm still learning RSS but it seems easy enough. I managed to create the RSS giving the file a PHP extension. When I tried saving it with an xml extension and adding a .htaccess file to the directory in which the file was saved, I get prompted to save the file instead of being able to view the file in a browser. The only line in the .htaccess file is AddType application/x-httpd-php xml. First off, and I'm sorry that this isn't a PHP specific question, but does RSS require an XML extension? And if it does, how do I get the server to serve the PHP file correctly if I rename it with the xml extension? Thanks, Robbert van Andel