When using the old form display portlet, not the "web form", several issues start to emerge if the reCaptcha is enabled on "Server Administration", for instance, the reCaptcha area simply does not show and several buttons like the portlet configuration becomes non accessible. Removing the captcha requirement solves the issue, while other components continue to use reCaptcha normally - which indicates that the keys are correctly configured on the administration area. Perhaps this behavior is a bug.
1-Create a form on the content area, it is not a web form
2-Append the form into a page for displaying
3-Enable reCaptcha on System Adminitration