First I would like to say: Thanks a lot !
The main way to support the app is to buy the Podcast Addict Donate app which is available on the Play Store and the Amazon App Store. It won't add any more feature, but it will remove the ads from the Podcast Addict app.
If you want to donate again/more, you can use the Paypal button available on this page ;)
You can also use Flattr