I have just installed SP Server 2013 Trial and SP Designer 2013 in the same machine. Using SP Designer 2013 gives me this error message:
This Web site must be created on a server that is running Microsoft SharePoint Foundation. Please choose another location.
Since SP Designer 2013 is free and is licensed, I presume that it cannot be used with a trial version of SP Server 2013, and therefore I must purchase the licensed SP Server 2013 to be able to use it with SP Designer 2013 (or just install SP Foundation 2013 since it is free and licensed too).
Am I correct? By the way, I am to create a big application out of SP Server 2013. I think SP Foundation 2013 will not suffice after reviewing its features and limitations.