help with mod_rewrite issue

I am trying to change the url http://www.mysite.com/folder/?fmt=rss to http://www.mysite.com/folder/rss.xml

Here is what I have in my .htaccess file right now

<IfModule mod_php5.c>
php_value session.use_only_cookies 1
php_value session.use_trans_sid 0
</IfModule>

<IfModule mod_rewrite.c>
Options +FollowSymLinks

RewriteEngine on

RewriteCond %{HTTP_HOST} ^mysite.com
RewriteRule (.*) http://www.mysite.com/$1 [R=301,L]

RewriteCond %{REQUEST_FILENAME} !-f
RewriteCond %{REQUEST_FILENAME} !-d
RewriteCond %{REQUEST_FILENAME} !-l

RewriteRule .* index.php [QSA,L]
</IfModule>

Code (markup):

I have tried this

rewriterule ^rss.xml$ ?fmt=rss [L]

Code (markup):

rewriterule (.*)\.xml$ ?fmt=$1 [L]

Code (markup):

 

RewriteRule ^rss\.xml$  /index.php?fmt=rss

Code (markup):

First clean up the clutter from the htaccess file, and I shall not be able to help you much in that, then the above code shall do exactly what you need

 

Clutter?? what do you mean?