How can I customize the content in aggregate blog RSS feeds?

To limit which blog posts are displayed on the site and in RSS feeds by default

1. Navigate to Administration > Applications > Blogs.
2. Click the Default presentation tab.
3. In Tags to filter Aggregate RSS, enter tags, separated by semicolons, which posts must include in order to be displayed on the site and group blog RSS feeds. If you leave the field blank (which is the default), all posts will be displayed.
4. Click Save to apply the settings.