Keeping this article simple for the timebeing
The source of the image holder in your RTF will have to be something that a QR Code API will return.
http://chart.apis.google.com/chart?cht=qr&chs=500×500&choe=UTF-8&chld=H&chl=http://www.jdesource.com
or
https://api.qrserver.com/v1/create-qr-code/?data=www.jdesource.com&size=500×500%22%20alt=%22%22%20title=%22%22
Ideally for dynamic images we use the URL
File System: url:{concat(../IMG_DIR_PATH,'/',IMGFILE)}
URL: url:{concat(../IMG_SERVER,'/',../IMG_DIR,'/',IMGFILE)}
For our case
URL: url:{'http://chart.apis.google.com/chart?cht=qr&chs=500x500&choe=UTF-8&chld=H&chl=http://www.jdesource.com'}
More info on the google apis – https://developers.google.com/chart/infographics/docs/qr_codes