In many cases we require to promote our newly launched blog. We can do it by adding RSS feed of newly launched blog to already running blog. To accomplish it, add this code where you want to display the posts:
wp_rss(‘http://newblog.com/external.php?type=RSS2’, 5); ?>
It takes the rss.php file that is built into WordPress In this code it is set to display the most recent 5 posts from the RSS feed of newblog.com. You can modify the number of post according to your requirement. Generally, wordpress user displays recent posts in the sidebar.