In our discussion of Darktable in “Post-Production Software 3” I briefly mentioned watermarks and proceeded to move on. I am grateful to announce that I have successfully added a watermark to Darktable and now able to discuss the details with you!
It really is as simple as Darktable makes it out to be in the resources section.
Having downloaded and installed “Inkscape”. I was able to import the image I created as my studio watermark and saved it off as an “SVG” file. Now that the “SVG” file is created, it can be moved to the watermark folder. The “watermark” folder may not be in the given file location listed in Darktable’s user manual. I did some searches and had each folder list its content until I found the “watermark” folder. Making sure to catalog the folder location I moved the “SVG” file into it and started the Darktable program to make sure it saw the file for watermarking. (If you place the watermarking file in the “watermark” folder while the program is running, use the reload button to the right of the watermark menu.)
Once your watermark is in place, you can change its position or check the box next to “blend” and change the layering modes as well as the opacity of the watermark.
One caution in using “Inkscape” for creating watermarks. When working with layers, be sure to merge all of your layers properly or you will come out with a blank box for text. For
example, below is an example of my mess-up. Watermarking the photo is no problem, however, I was hoping to display my website URL while claiming the intellectual rights of my photograph.
As you can see in the lower right hand side there is a short, white rectangle which was supposed to contain my website URL. I cannot win them all, I guess! This is a good illustration though of learning from mistakes instead of letting the mess-up dictate my choices and attitudes. Each mess-up is an opportunity to learn something new!
Foe-toss | LIGHT 
Hello, I have a problem with Darktable. I’ve just installed on my MAC, but I cannot find the directory to put my custom watermark. I searched the file .config and the folder darktable but in all cases don’t appear the mentioned directories, so I can,t copy mu watermark… Can you help me? In your post I’m not able to find the answer. Thank you very much.
Hello Eva, in the MAC finder you will find the Darktable application executable in “Applications”. Use your secondary (right) mouse click and select “Show Package Contents”. You can place your watermark image saved in an “sag” format in the following folder at the end of this file path: “Contents” -> “Resources” -> “share” -> “darktable” -> “watermarks”.
I apologize of the horrible 2 year delayed response. I hope this helps you and others who read.