This extra support is now included as an option in the original thing. So this one is now redundant.
This is a special version of the top holder for the Universal Charging Dock found here: http://www.thingiverse.com/thing:1655546
This version will hold the phone better, if you want to use the dock in a car or a boat.
For this one you also need to measure the total thickness of your phone.
Click on the customizer to get started.