title: Tumblr RSS feed that only contains specific tags
body: <p>I want to create a RSS feed based on the Tumblr tags I use. I want to submit <strong><em>some</em></strong> of my posts to a blog syndication service. To the blog syndicator I have to provide a RSS feed. But I don't want all posts to appear there. Is there a way I can do something like this?</p>
  
  <ul>
  <li>When I tag a post with a specific keyword: (eg: #blog) the post will
  get added to the RSS feed. </li>
  <li>If the #blog tag is not there, the post doesn't get included to the RSS feed.</li>
  </ul>