Your content type is application/rss+xml
. In that way it will never show up as html.
Just remove the ContentType="application/rss+xml"
part or replace it with text/html
and change your page to be html instead of rss.
There is no way to tell the browser: hey, you should read rss but format it like html. You can combine things (so rss tags in your html), but it will evaluate the way the browser thinks best (and that is not what you want).
Just output html from your rss reading and format it as html.