URL Rewrite /foobar/rss to rss.php?username=foobar

I already use URL Rewriting to rewrite /foobar to index.php?username=foob开发者_Python百科ar using:

RewriteRule ^([^/.]+)$ /index.php?username=$1 [QSA,L]

What should I add to also rewrite /foobar/rss to rss.php?username=foobar?

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This is how it's done:

RewriteRule ^([^/]+)/rss$ /rss.php?username=$1 [QSA,L]