I just figure out how to pull in and show the feed defined by each user from their profile page and show up in the author page.
We find code at http://codex.wordpress.org/Function_Reference/fetch_rss
to fetch rss feed. I just tweak this
Instead of $rss = fetch_rss('http://example.com/rss/feed/goes/here');
I replace this as
$member_blogs = esc_attr(get_the_author_meta('rssfeed', $user->ID));
foreach ( (array) $member_blogs as $feed_url );
$items_fetched = 0;
$rss = fetch_rss( trim( $feed_url ) );
That's all! you can see full post on this at
http://blogcastor.com/show-external-blog-post-in-wordpress-author-page/