To configure IIS with Kerberos,

It is explained in the technet blog:

In short, you must follow the Technet blog, you  must configure your IIS to use Kerberos authentication (IIS manager option) and for constrained delegation (remove the default applicationpool where your web service is running) create a specific technical domain account ie. mydomain\acctiiskerb

Then assigned to this account, a SPN must be created (on our side only),
using the command like: Setspn -a HTTP/iisserver.mydomain.local acctiiskerb

and modify the acctiiskerb settings (using the ADUC: Delegation TAB for this user account must be also configured properly).