Your RSS feed is a digital definition of your podcast. It tells podcast apps where you download your podcast and provides all the metadata (e.g. tilte, description, etc) about your content.
On RedCircle, you can find a link to your RSS feed on the Podcast's page. Visit the podcast list page and click on the podcast that you want the RSS feed for. On the podcast page, click the blue copy icon next to RSS Feed below the podcast description. This will copy your RSS feed link, so you can paste it elsewhere (ie. in a new browser tab):