Apple - How do I transfer my iOS developer profile to another computer?
Import/Export works differently in Xcode 5+. This Apple Developer guide shows you how to do it.
Your account is shown under Xcode → Preferences → Accounts, and can be exported by clicking the gear icon () in the lower-left.
You can do this from within Xcode.
From the Organiser, on the devices tab, you can export your developer profile to a file which you can then import into Xcode on another computer.
The step by step process is explained in http://developer.apple.com/library/ios/#documentation/ToolsLanguages/Conceptual/Xcode4UserGuide/080-Manage_Your_Devices/manage_devices.html near the bottom in the section entitled Transfer Your Developer Profile to Another Computer
Note that if you don't have a Teams section in your Organizer - Devices, you can just drag and drop the password-protected Developer profiles export-file, onto the Xcode icon in the toolbar.
You need to export your private key from Key Chain access of Mac OSX in which certificates are running successfully or from which developer certificate made and download certificates from Apple Developer Portal, it will work as it works for me.