So you place the document on a table, you start the process on your Mac and than you take the iOS device to take a picture. The yellow area shows where the document is recognized, so you can scan it. iOS will do the crop and rectify steps and store the document as PDF. I needed, you can add more pages.
We'll also offer the possibility to show the popup menu with all options including selecting device for more than one of them. Screenshot is in German, but the texts are actually localized to your language.