OK, with some  help from  David Kimura I got it working with credentails and corrected my 'copy and paste' error from facebook Oauth strategy. Lesson learnt is about the escape character /n that must be used when specifying the key in the credentials file, something about the conversion to 64 bit ..... ( error you get from Apple will be something along the lines of 'OpenSSL::PKey::ECError, invalid curve name'. Thanks again to David for his prompt help.