This week, ReadKit started crashing for me as soon as I opened it. No matter if I tried to refresh, click on a tab or open the preferences it crashed. I can only assume that it was something to do with my subscriptions that caused the error.
I decided to clear everything and start again in ReadKit, and the issue was solved.
Open Finder, then in the menu bar select
Go to folder... and paste in the following path:
Once that folder opens, rename
ReadKit.storedata.old and restart ReadKit. All your subscriptions should be missing, but ReadKit should no longer crash. Reconnect all your services, and you're good to go.