Feeds that require http authentication are recently supported. Please try to use the following format, when you add your feed URL to the subscriptions:
https://user:password@example.com/feed.xml

It is important to note that such feed format will ony work with Standalone RSS service. (you can easily add it to your services with the bottom left + button)

This might not work properly for SSL feeds, but we are recently working on addressing the issue. In a future version proper management of password protected feeds will show up.

For Basecamp users this should work:
https://{API token}:password@foo.basecamphq.com/feed/recent_items_rss

rockysandstudio.com
Category: News, Feedly, Feedbin, RSS
Compatibility: MAC OS X Yosemite, El Capitan
Leaf: News Reader for Mac OS X (Yosemite, El Capitan)

Leaf is an amazing news reader for Mac OS X (Yosemite, El Capitan). Read, share, star and search news from all of your favourite websites by using a clean, intuitive, OS X Yosemite, El Capitan-style next generation interface. Leaf is supported feedly and feedbin. Feedly App for Mac OS X, Feedbin App for Mac OS X