No HTTPS on Credit Card entry form - Can it be safe?

I was going to make a purchase on a website, but the page containing the Credit Card entry form is HTTP and HTTPS. Is it definitely unsafe?

The website advertise the use of "RapidSSL" but if I send my credit card number through HTTP I don't really get it... Is pressing next on this page a security concern?

http://imgur.com/IVmvo3f