If you're using Acrobat, click on the email icon in the viewer's menu bar.

(If your Adobe toolbar's missing this icon, just control-click or right-click somewhere on the toolbar, scroll down to "More Tools...", and add it.)
If you're using Safari's PDF viewer on a Mac and use OS X Mail
as your mail client, control-click (Mac) on the PDF and select
"Print Frame...". In the dialog box, click on the PDF button in
the lower left-hand corner, and select "Mail PDF."

If you don't use the OS X Mail client, save the PDF and attach it to your email as you would any other attachment.
Save the PDF and attach it to your email as you would any other attachment.
Please remember to be mindful of Pubget's acceptable use policy and respectful of any and all fair use policies of the content providers and institutions through which you may be gaining access.