No identities are available for signing Xcode 5
All you need to do is:
go to Certificates, Identifiers & Profiles in the Developer Center
create a new provisioning profile in "Provisioning Profiles" / "Distribution"
download the profile and open it
restart Xcode
Please make sure you are using distribution provisioning profiles, rather than Development.And the code sign setting in Xcode is compatible with the distribution provisioning profiles.
The validation process does not work with Ad-hoc profiles. Need to create a Distribution provisioning profile. It is not specified in the instructions for beta testing. I agonized all day until realized.