When I try to use Xcode5 dp6 to run app on devices. I got an error of
No Provisioning Profiles with a valid Signing identity found issue
I had exactly the same issue and I manage to sort it by deleting provisioning certificate from Keychain app and I download it again via Xcode (Xcode -> Preferences... -> Accounts). If it doesn't help try remove certificate and provisioning profile. After than make sure you set up everything right in Build Settings (Code signing). Hope this help