iOS8 - Open podcasts app via website link?
Based on this answer, feed://podcasturl... or pcast://podcasturl... both work, though slightly differently.

With my tests today, using Chrome for IOS, feed:// opens up the podcast app with the "Add a Podcast by URL..." popup with your podcast feed already populated. All you have to do is press Subscribe
If I use Safari, it tries to use a feed reader app, like Reeder.

pcast:// seems to open your podcast so the user can browse the published episodes.

Note: the pcast:// option didn't work for me, possible because this is a private podcast used for testing, and not published to Apple iTunes.