Short answer: No. DPP has no add watermark feature.
There is a convoluted way to add watermarks via Digital Photo Professional, but it isn't remotely efficient enough to make it worth the trouble.
Once you've done all the editing you wish to your file, you can use the compositing tool to combine that image with another. Although the compositing tool can handle raw images, it can only do so if both images are in raw format and shot with the same model camera. So for adding a watermark you would need to create a JPEG version of your image after editing the raw file. The other image would be one containing the watermark. When combining the two images, if your watermark template has a black background use the "add" option to combine the two images. Since the black background would have pixel values of (0,0,0) the only part of your image affected would be the part where the white watermark is added. If your watermark template image has a white background you could use the "darken" option in the compositing tool and place the watermark image in the foreground. You could also use the "lighten" option with a watermark image using a black background by placing it as the foreground image.
You would need to create the image containing the watermark using an application that can create a uniform black or white background and allow you to add your logo or text before exporting as a jpeg using minimal compression. You might also need to size it to the same exact dimensions as the image you wish to watermark. The composite tool does allow you to alter the position of one image in relation to the other, but it isn't clear if you can combine images of two different sizes. You may well be able to do so.
For complete instructions on how to use the Compositing Tool in DPP4, please see pages 97-100 of the Digital Photo Professional Ver.4.3 Instruction Manual.