Donate link rel=payment from shownotes
Other podcatchers (like overcast) support a $-Link generated from shownotes.
<a href="anylinktodonate" rel="payment">Some text</a> will enable a Button in the player which just opens the browser.
https://overcast.fm/podcasterinfo -> Payment button
Podcast Addict has been supporting this for the past few years
In case you have some issues with a feed please send me an url with more details (Settings/Feedback)
Sebastian Stix commented
GREAT! I can't see this option in the UI. See only flattr-button.