When you receive documents from your friends, classmates, colleagues, and clients via messaging apps, how to save them to PDF Reader?
Open in to PDF Reader (Using WhatsApp as an example)
1. Tap on the file you want to save to PDF Reader and tap the "Export" button on the bottom left corner of the screen
2. Choose "Share" from the menu
3. Choose "Copy to PDF Reader"
4. Then the file will be saved to the file list in PDF Reader.