[exim] DomainKey again... DNS configuration

Hi, list!

First of all, thank a lot for your answers.
Now I think I know how to configure my Exim to use the DomainKeys.

I have another problem, now: I didn't found any documentation/howto/example to
create the DNS-entries for my domain.
Of course, I read domainkeys.sf.net, but I didn't found any docs with what the
field in the TXT-entry mean...

Can someone suggest me an URL with this information?

Thanks a lot!
Luca Bertoncello
(lucabert@???)