Under the Review tab, create a watermarked pdf proof which you can then send to your customer in your preferred manner (email attachment, file transfer service, etc.)
Set up your render options: add a file name and a page range to render.
You can choose to add your own company watermark (this works best with a png file with transparency).
Choose to overlay the image file names onto the proof, to help identify photos in your layouts when discussing the project with clients.
Click on Render to produce the file to create a pdf with your choice of applied settings. The rendered pdf will be saved to Documents\Memento\Projects\Proof PDF by default.
Customer proofs render at the trim line of the page, to give an accurate depiction of the finished album.