When I try to use the spec within the portal. Home-> APIS->API DETAILS->Spec I can select an application, an api key and the Authorize is filled with the selected apiKey and I can try an to test an operation.
If I do the same steps in de API HUB the apikey isn't filled in the authorize tab.
Although I select the application and api key. So now a consumer must first go to the application, select an application, copy the apikey and go back to the APIs TAB and copy the api-key in the api-key in authorization.
This is a know limitation and will be fixed in API Portal 5.4