How to add the xcconfig file in plist for custom Xcode template?

Question

I am trying to write my own Xcode template, now I have a problem for pointing Xcode to my custom xcconfig file. I already add the config files in the project, now I am not sure what's the key for setting it so Xcode knows, any ideas?

This is what I have so far.. Don't know what should go under release, or if it even is under configurations.

<dict>
    <key>Configurations</key>
    <dict>
        <key>Release</key>
        <dict/>
    </dict>
</dict>