While applying RE, choose "Embedded File Attachments" option. This will permit users to add attachments to the PDF document.
~ Varun Nohria
Thanks for your quick reply!
Although your response did not state, I'm assuming this feature is only available with Livecycle Server which I do not have. Are there any other options?
Of course. This facility is only available with Reader extension server. You need to apply reader Extension permissions for the form and specifically , you need to add Embedded File Attachments reader extension.