As much as I love DevonThink Pro (which is to say, a lot) I don't like this workflow. Only because it immediately launches the app. And because I rely on DevonThink Pro so heavily, and because it's a rich and complex app, it takes a while to open. And I rarely want to immediately go into the app when I'm filing a PDF. I'm just stuffing it away for future action.
So I finally took the time to create an alternative. It's so easy, I should have done it a long time ago. And you should do it too. Instead of launching DevonThink Pro, it saves the PDF to the DevonThink Inbox folder. From which it will be automatically imported the next time you launch DevonThink. So the end result is exactly the same, but without the interruption.
Here's how you set this up. Next time you print something, click the PDF button in the Print dialog, then choose Edit Menu. (You can see it at the bottom of the list in the screenshot above.) Then click the Add button in the workflow list (shown in the screenshot below) then pick your InBox as the destination. This screenshot shows what it looks like when you've done this:
That's it, you're finished. Next time you want to stash a PDF in DevonThink, click the PDF button, click InBox, and then you're done. And back to work.