There are two ways to attach a PDF to an email, depending on if you want the PDF to ALWAYS be attached to an email template, or if you only want to manually attach a PDF occasionally, or only attach it to specific emails.
1. Manually attach PDF to an Email.
First, make sure the PDF is uploaded to the Documents Tab. Next, once you are creating the email, you can attach the PDF by clicking the 'Add Attachment' button at the bottom of the screen, then selecting the appropriate folder where the PDF has been uploaded (ex. 'Templates-Appointment').
This can be done when:
a) Sending an ad-hoc email OR
b) When selecting a document to send via email via the 'Print/Email' button and selecting @ 'Send in an email as the email body' OR
c) When selecting a document to send via email via the 'Print/Email' button and selecting the paperclip 'Send in an email as PDF attachment'. 
2. Attach PDF to an Email Template
With this option, the PDF will send as an attachment EVERY time the email template is used.
Navigate to Setup > Personal Setup > Email > My Templates. Select the Template to which you would like to add the PDF. Click on the 'Email Template Name'. Once on the Template detail page, scroll all the way down to the bottom of the screen, past the preview boxes. Click on 'Attach File' to select your attachment.
From the popup window, select whether you would like to upload a file from your Computer OR select the appropriate folder from the Documents uploaded in your improveit 360 Documents Tab. Click Save when finished.
