using System.IO;

using MimeKit;

using MimeKit.Cryptography;

​

// ...

​

string privateKeyPath = "path/to/your/private_key.pem";

string domain = "yourdomain.com";

string selector = "your_selector";

​

using (var stream = File.OpenRead(privateKeyPath))

{

    var signer = new DkimSigner(stream, domain, selector, DkimSignatureAlgorithm.RsaSha256);

    // Use the signer to sign your message

    // message.Sign(signer);

}