Recaptcha on dynamic submit form

I want to add recaptcha on a form with validation in JS/Ajax.
How can I do with your plugin?

Sample :
<form onsubmit=”submit(event,this);”>
<?php do_action(‘google_invre_render_widget_action’); ?>
</form>

well, the request is sent to the recaptcha API but submit(event,this) is not called

Thanks,