To use this in the HTML form Builder download this file (inksig.zip) and extract it to the location of your choice.

Now publish all the files to your server. Now create a form in the form builder and add a html element. Now paste the code below into it and adjust the iframe src to the location to where you placed the inksig directory. Just make sure it points to the require-drawn-signature.html. If you have the iframe and the files all done correctly the signature pad will show in the form builder instantly during the design process.

<iframe src="http://mydomain.com/inksig/sig/require-drawn-signature.html" width="250" height="320" scrolling="no" frameborder="0"></iframe>