In MacPractice 11, you're able to send and share attachments to a patient's record on the Patient Portal. Doing so is quite easy.
First you'll need to make sure that the Attachment in question is associated with the Patient account you wish to share the attachment to.
Then, in the Attachments Ability, in the upper right hand corner, there is a "Share to Portal" checkbox you'll need to check.
This will ensure when the patient accesses their records via the Patient Portal, this attachment will be available. They will be located in the "Shared Files" tab on the Patient Portal, as shown in the screenshot below.