Dear TattooedMac, thank you once again. Watermark Sense is exactly what I was looking for. Generally I just reduce the size of posted photo images but lately (due to the purchase of a new camera) my wife has wanted to post/send full size/resolution shots but did not want them to become public property. We tried (there are a lot of them) several apps, Watermark Pro, iWatermark etc but they were either very complex to set up or, did not have the options my wife wanted.
I have tried this app and it looks perfect on OSX 10.10.4 I will give it a try on the Beta 10.11 later hopefully it will work just as well.
A big thank you for saving me a lot of time.
Kudos to you,
Rod