In Magento Enterprise we have the default settings for Return Merchandise Authorizations to be enabled on the fronted and by product. However, when we test this feature as a guest or registered customer there is no way to return a product (no link in footer for orders and returns and no link on registered customer account dashboard). As an admin we are able to create RMAs and complete them. Is there something else we need to do for this feature to be accessible to our customers?
I would suggest you try to access : /sales/guest/form to check whether the functionality is really enabled or not. From there we should be able to drill down to the root cause of the issue.