HTTPS for every page except for feeds

Our site has a persistent login form on every page of the site, so of course we need to keep every page served over SSL. However, we've since discovered that Feedburner doesn't like secure feeds.

Is there a way to deliver the entire site via https, except for "http://nplusonemag.com/feed"? .htaccess? Action hook?

Edit: I should have shared my .htaccess rules. These are obviously not working.

RewriteCond %{HTTPS} off
RewriteCond %{REQUEST_URI} !/(feed|robots\.txt|favicon.ico) [NC]
RewriteRule ^(.*)$ https://nplusonemag.com/$1 [R=301,L]

# Force non-SSL for certain URLs
RewriteCond %{HTTPS} on
RewriteRule ^(feed|robots\.txt|favicon.ico)$ http://nplusonemag.com/$1 [R=301,L]