Failing to add Threat Intelligence Feed to Splunk Enterprise Security with custom HTTP Authorization Header

[splunker21666]

Hi

I would like to add an additional Threat Intelligence Feed to the collection of the Intelligence Downloads in Enterprise Security. 
The Service-URL needs to have an authorization header to allow the HTTPS call.
So far i can't find any options within Intelligence Download Settings to add a custom HTTP-header with authorization Information like an API key.

Is there any option in the Standard configuration of Intelligence Downloads to add a custom HTTP-Header to the requests?

Or is there another extended configuration possibility?

Thx for feedback.