Need to create a “void” pantograph or something similar

I’m developing an app that, among other things, will allow mental health practitioners to create and print prescriptions for their patients. There are requirements that specify that prescriptions have to be written on tamper-resistant pads and/or meet certain other specifications to help ensure that people don’t make copies of their scripts to share with their friends. (The resources I’m using for this info are here: http://tinyurl.com/mh8fxgk and http://tinyurl.com/kmvufqz )

If I’m reading the specs correctly, an EHR can be used to print a script on plain paper if the digital script meets at least 2 of the requirements listed in the resources above. The first one they suggest is a “microprinting” thing that uses a tiny font size which won’t copy well so that sounds easy to do. However, finding another one to implement has me stumped. For example, look at this paragraph:

“The second feature is a “void” pantograph accompanied by a reverse “Rx”, which causes a word such as “Void,” “Illegal,” or “Copy” to appear when the prescription is photocopied. Except where state law mandates the word “Void” or “Illegal”, it is recommended that the pantograph show the word “Copy” if the prescription is copied.”

I have no clue how to do something like this, especially since I have no control over what kind of printers my users will have. Almost all of my target audience will likely just be using regular home printers - nothing fancy. Anyone know what that paragraph means or how to implement it?

Another option that’s suggested is to use a weak digital watermark. I can certainly put a low opacity image on the scripts. I’m just not sure if that would satisfy the requirement or not.

Any help will be most appreciated.