AirPrint is an Apple technology. PDF is just a file format.
Unfortunately, Adobe Acrobat Reader for iOS has no control over PDF generation using Apple's AirPrint on iOS.
Sorry for the inconvenience.
I think I know how to do it and will like to share with the community users in this forum, who may be asking the same question. MobileDeveloperCK, please put this up as the official reply to my own problem. This is for iOS 10 in iPhone 6 and I am using the scenario where I want to print an email message in the Mail app.
1) Go to the Mail app in iOS.
2) Choose the email message that you want to print
3) At the bottom of the screen, choose the "reply" icon, or the 4th icon.
4) Tap on "Print"
5) Use two fingers and pinch out the print preview of the email message.
6) Tap on the "share" icon at the bottom left of the screen
7) If you have downloaded the Adobe Acrobat app, scroll to your left and select "Copy to Adobe Acrobat"
8) Choose the "Share" icon or the 4th icon at the bottom of your screen
9) Tap "Share File"
10) Choose either "Share Original Document", which will make comments and forms editable but it will not be viewable by some apps, including Mail app in iOS, or "Share Flattened Copy", which will make comments and forms uneditable but will be viewable in most apps.
11) Select the app that you want to share the file to, eg. Mail.
12) That's it.
For questions relating to point 10, please ask MobileDeveloperCK. This person is supposed to know how this works.
Thank you for sharing the information in the user forum!
Here's another article.
It sounds like a very useful feature.
Just to be clear, it's a new feature of iOS 10, not Adobe Acrobat Reader.