By default the rss feed url is https://www.reddit.com/.rss and total items will be shown is 10
Assume the site name is http://localhost.rss/
To specify other url other then the default one pass the url as query paramter with name "feed_url" and to modify the item count the parameter name is "size"
eg: http://localhost.rss/?size=20&feed_url=http://feeds.feedburner.com/ndtvsports-cricket