Does anyone know how to electronically sign a doent?

You attach a certificate to it that you get from any of the certificate authorities like Verisign. Here is where you buy them: a href="http://www.verisign.com/products-services/security-services/pki/pki-application/trusted-messaging/index.html" rel="nofollow"http://www.verisign.com/products-service…/a