Recaptcha that works on Responsive Classifieds theme.

Hi guys, can anyone help me i need a recaptcha spam plugin that works on the responsive classifieds theme, i have the Allow Visitor Submissions activated as i don’t want the user to register first,as this worked for me on the non responsive classifieds theme, but i keep getting spam registrations and spam listings, does anyone no any plugins that work with the responsive framework.
thanks Candice

https://www.carsforsaleinhull.co.uk