I recently added my RSS feeds to FeedBurner .
Here is what is worked for me.

My blog is located in /blog directory you may need to change RewriteBase if your blog is installed in another directory. Additionally you'll have to change YOUR_BLOG_ID to match your provided by FeedBurner.

In the .htaccess rules we allow FeedBurner itself to retrieve the feeds otherwise there will be an infinite loop.

RewriteEngine On
RewriteBase /blog/

# Enable FeedBurner services
RewriteCond %{HTTP_USER_AGENT} !^(FeedBurner|FeedValidator)
RewriteRule ^feed http://feeds.feedburner.com/YOUR_BLOG_ID [R=307,L]