Clipping your friction hitch to your harness leg loop is not reccomended. From \"The International Handbook of Technical Mountaineering\" by Peter Hill:
\"A place that is convenient to clip the prusik loop is on to a leg loop, and this practice has continued for many years. However, anyone considering using this method should be aware of two major problems. Firstly, if the abseiler is rendered unconcious by stone fall or similar and is hanging in their harness, their bodyweight will cause them to rotate slowly until the prusik touches the abseil device and fails. Secondly, should the abseiler tilt to their side when using the system in the lock-off position, such as when retrieving gear or assisting an injured climber, the French prusik could touch the top of the abseil device, causing it to fail.\"
Since you are already using an extender, clip your friction hitch onto your belay loop and position the frition hitch below your abseil device. A friction hitch positioned above your belay device is generally more difficult to release once locked up. Have a look at http://www.samountainmag.com/back-issue ... icle_ID=43
. Specifically look at method three.