add or create ‘Subject Alternative Name’ field to self-signed certificate using makecert

An even easier way is to use the New-SelfSignedCertificate PowerShell commandlet, which includes a SAN by default. In a single command you can create the certificate and add it to the store.

New-SelfSignedCertificate -DnsName localhost -CertStoreLocation cert:\LocalMachine\My

Note that you need to run PowerShell as an administrator.