I'm building a site for a client that allows members to sign up through a standard CiviContribute contribution page. I have a requirement from the client to allow users to select from a free membership type that should appear along side the other paid options. I've tried a few different ways of doing it, but it seems like it doesn't work when "Execute real-time monetary transactions" is enabled to allow users to checkout with PayPal. The free member type option still shows up, however selecting it causes the "check out with PayPal" submit button to disappear and no other submit button appears to replace it. It actually is still possible to submit the form with the free member type selected by pressing enter in one of the text fields, but it doesn't seem to me like this is the correct behaviour.
Is it possible and supported to offer the option of a free membership type along side paid ones as I'm trying to do?