How to include in wp_login_form

Hi,
We are using your plugin in our site since long.
It is very good plugin. Good Work.

Now we need to create a My account page. On this page, we have added a login page using function wp_login_form. The login form displays fine, but when one tries to login , the page throws error of incorrect captcha.

How can i add the captcha to this form?

The page I need help with: [log in to see the link]