Specify [realms] for heimdal in Network Identity Manager

This is a question about NIM which I learned is based on Heimdal
nowadays.

I tried to specify custom realm settings for NIM.

So I went to the Options->Kerberosv5 and edited the
   C:\ProgramData\Kerberos\krb5.conf
file mentioned there. However, even if I write
someting completely silly there like

[realms]
 NADA.KTH.SE = {
     kdc = tcp/1.2.3.4
 }

NIM still can obtain tickets which it in my opinion should not, especially if I have

[libdefaults]
  dns_lookup_kdc = false

So is this file ignored?

Is the config somewhere else?

What I actually want to config is

NADA.KTH.SE = {
   kdc = http/130.237.232.194
}

Which works fine in the normal Heimdal distro.

I am trying as well to change the default realm setting in NIM but
ATHENA.MIT.EDU keeps coming back.

Harald.