You should be able to go to "my profile" at the top of the page, then click the "download certificate" button under the respective passed exam attempt. This will open a PDF file you can print yourself, which has your name, certification, and date of obtainment on it. It also includes a digital signature from Ken Schwaber. This is meant to be your "hard-copy" certificate.
If you want an actual ink signature, I'm not sure they do that. You could use the Support Center link and contact the site staff directly with that question.