Signing an application
Signing applications on OS X is done using the codesign command line tool.
If you do not already have XCode installed then you can install it from the Mac App Store.
Install the command line tools
From the XCode Preferences, navigate to the Downloads pane. If the Command Line Tools are are not installed then click the Install button.
Signing the application
Visit https://gist.github.com/trevordevore/3e91724c4573690b691510d2e2dcd2a7 and download the file using the "Download Zip" button.
In the ZIP archive is a signOSXApplication.livecodescript file. Open it in LiveCode. Click on the Sign Application button to sign your app. You will be prompted to select the executable and provide the name of your developer certificate.