If you have submitted your RSS feed to Apple Podcasts, and it was rejected, you have the chance to resubmit it again. Before resubmitting, make sure of the following:

1. Your image artwork is at least 1400x1400 pixels. Learn how to check your image's dimensions here. 
2. If your podcast’s content is explicit, you have check-marked the Explicit Content box on your Content Settings page.
3. You have at least one track in your RSS feed.
4. Make sure that it is a valid feed by copy-pasting the RSS feed from your Content Settings page here.

I resubmitted and got an error message from Apple Podcasts

If you submit to Apple Podcasts again, and get the error ‘Feed has already been submitted’, then you will have to speak to Apple directly. They need to clear their directory’s cache in order to recognize your feed as not submitted. As a hosting provider, SoundCloud has no influence over Apple in this matter. 

You can contact Apple Podcasts support by clicking the “Contact Us” link at the bottom, here:

https://podcasters.apple.com/support/