I have redirected my WordPress RSS feed (domain.com/feed) to FeedBurner, and made the FeedBurner feed the one publicly visible.
Still, the URL of the WordPress RSS feed is the standard for any WordPress blog (…/feed), and I have noticed that many readers are manually setting their RSS to this feed rather the FeedBurner url.
How can I change WordPress’ feed address so that it is private to the public, but still available to FeedBurner?
You need to look for a plugin called Feedsmith. It does this perfectly.
there are many ways to do that ,but this plugin do it easily for you , just enable and set security token:
https://wordpress.org/plugins/feed-changer/