seandavey my bad, I misunderstood what's going here.
The TXT record you have published right now is for
demo._domainkey.cohousing.site. This breaks down like so:
demo is the selector
_domainkey tells DNS that this is a DKIM record
cohousing.site is the DNS name associated with the record.
So, what you have here is a not a DKIM record for demo.cohousing.site. It is a DKIM record for cohousing.site using
demo as the selector.
As I mentioned earlier, you already have an DKIM record published for demo.cohousing.site under the name
dkim._domainkey.demo.cohousing.site. This is something we manage behind the scenes so it doesn't appear in your domain list in the dashboard. If you're sending mail from a private mail server and want to use that key to sign your outgoing mail then please contact support to get your private key.
If you want to publish another DKIM record for demo.cohousing.site using
demo as the selector (instead of
dkim) then create a new subdomain
demo._domainkey.demo.cohousing.site and add the record to that. You'll then need to use your own private key to sign your outgoing mail on your private SMTP server.