I?
Thats for Android.
for iOS tho, I think Paperback got shut down.
so I use Tachimanga which you can find in the app store. However, unlike Kotatsu which comes with sources already in the app, you have to go to tachimanga website in the safari browser and click their sources link and that automatically adds the way to select which extensions to add. I think this is how Tachimanga circumvents being banned from the Apple App store. I think its smart but it would be safer if they used a link not on their site namean.