Thank you for the positive comments. I'm glad my article was helpful. :-)
Herbert, yes, Brian is correct. The UI I'm referring to is the dialog box you see when you add a Linked Server in the Management Studio GUI.
OPC.Three, I used 2 servers for this setup with both using the same dedicated domain account. (This is not necessarily a best practice for production, BTW.) I constrained the account to just being trusted for delegation to the SQL services on each machine. And I allow NTLM. (I have no Kerberos requirement.)
In the account properties dialog, when you choose to constrain to certain services, those running on all servers for which you've registered SPNs should show up automatically.
And the SPN command is all over the web now, but here it is again:
setspn -A MSSQLSvc/server:port|instance acct , and:
setspn -A MSSQLSvc/server.domain.tld:port|instance acct
Both must be issued for domain account Linked Servers, per documentation.
BTW, if your doing this for a clustered server, server must be its virtual name.