1- Open Adobe Acrobat Pro to watermark PDF files
2- Click File option and then Open button
3- Browse PDF in which you want to add watermark
4- Go to Document option and click on Add Watermark & Background
5- Choose to Add a Watermark option
6- From Source box select any option 'From Text' or 'From File'
7- If you select Text then, add appropriate text and set its size and color
8- For file option select the appropriate file or image
9- Now, set the position and appearance of the watermark
10-
Set the page range in which want has to be added and then,
click OK