reCaptcha gets added at wrong position in drupal form

I have sign form which needs have captcha authentication. I installed Captcha and reCaptcha modules in my Drupal 7 project.
When I added checkbox recaptcha it gets added successfully but after the form submit button.

This form is placed in Block under right sidebar and the form is created using function drupal_get_form. On form submit a function get called. Form didn't have submit button instead has image with submit title, drupal_render is used to render form.

Please find attached image which shows position of captcha on form.