by logging into your libsyn account and clicking the “settings” tab, then click “advanced” settings. Under “public rss” url, add your new feed url, and also select the checkbox to “redirect to this URL”.
Once you save these settings, when your libsyn.com feed is requested, clients will receive a 301 redirect to your new feed.
The 301 redirect will take care of existing subscribers, but it may not update the iTunes podcast directory with your new URL. You should also include the <itunes:new-feed-url> tag in your old feed to ensure that new subscribers who find you in the directory will be directed to the correct feed. The feed format is:
<itunes:new-feed-url>http://newlocation.com/example.rss</itunes:new-feed-url>
After adding the tag to your old feed, you should maintain the old feed for 48 hours before retiring it. At that point, iTunes will have updated the directory with the new feed URL.