If your podcast is hosted on Wordpress and you are using the plugin PowerPress Plugin (https://wordpress.org/plugins/powerpress/) to generate your podcast feed RSS you are able to redirect your podcast feed to RSS.com you have to follow these steps:

1. Install the plugin "Redirection" (https://wordpress.org/plugins/redirection/)

2. Activate the plugin

3. Access the redirect plugin clicking by "Tools" > "Redirection" 

4. Add a new Redirect clicking by the "Add new" button

5. Your feed setup is usually https://yourcustomdomain/feed/podcasts/ so your setup will be:

Source URL: /feed/podcast/

Query parameters: exact match in any order

Target URL: your new RSS.com RSS feed URL

Group: redirections

6. Click "Add redirect" button

7. If you activated have any kind of cache inside your Wordpress installation you have to clear your Wordpress cache.