Hello marweis,
Please add
error_reporting(15);
line to the file at beginning :
wp-content/plugins/responsive-contact-form/include/captcha_code_file.php
and try to execute file as following,
http://www.yourdomain.com/wp-content/plugins/responsive-contact-form/include/captcha_code_file.php
It must display a captcha code image.
If it throws error, Please provide us that error so we can provide a solution to you.
Captcha code is generated using GD library functions which may not be supported by your server.
Thanks & Regards,
August Infotech
