Setting up multidomain DKIM with Exim

I was recently setting up SPF, DKIM and DMARC for multiple domains and was having trouble getting Exim to sign emails for the different domains. I found an article here explaining the steps. But I kept getting the following error in my exim logs: failed to expand dkim_private_key: missing or misplaced { or } The suggested configuration was the following:

I’m not quite […]