[exim] spf info in the "Authentication-Results:" header?

Dear Colleagues,

I have the following configuration:

acl_smtp_dkim = acl_check_dkim
begin acl
acl_check_dkim:
   accept add_header      = :at_start:${authresults {$primary_hostname}}

However I see only the iprev= and dkim= results in the resulting
"Authentication-Results:" header. What and where should I add to also
see the SPF results there?

On another box elsewhere, I have an "spf = fail" check in
acl_check_mail, but on this box, I don't want to block incoming mail on
SPF failure, I just want the result of SPF validation to appear in the
"Authentication-Results".

--
Victor Sudakov VAS4-RIPE
http://vas.tomsk.ru/
2:5005/49@fidonet