Sadly, Reeder no longer supports other RSS feed clients like Feedbin and Feedly.

Why doesn’t this version of Reeder support third-party sync services?

With the new Reeder, tracking what you’ve read is based on your scroll position rather than traditional read/unread states. This design makes integration with most third-party sync services non-trivial, so support for these services is not currently planned.

— Reeder Help

This change away from unread/read states on posts is probably my biggest concern with the new Reeder app. Scroll positions have been used in similar applications to determine how much you read. From my memory, I didn’t use this feature in the applications that implemented it. I was happy to start scrolling from the latest posts and scan back as far as I wanted. It’s early days, though, and I haven’t even added any significant number of feeds to Reeder to see how effective this will work.

That is the beauty of unread/read states, though. Minimal thinking is required to determine what’s left to read. I know from a glance what I need to catch up on. Scroll positions require me to scroll to catch up to the point where there’s nothing left in my timeline to see. I would much rather click through collections of feeds and see precisely what’s left to read.

For now, though, I’ll keep Reeder Classic on my iPhone, but I can see myself using Feedbin’s iOS app instead of Reeder Classic over time. I imagine there will come a time when Reeder Classic won’t be supported. When that time comes, I would prefer to use an alternative to Reeder Classic daily rather than be forced to make the change away from it.