These instructions are for images destined for the web but can be used for watermarking any image, not just for the web.
One of the major advantages in Lightroom is that it handles all processing and edits of images in a nondestructive way. Simply, all changes and edits are recorded by Lightroom but NO changes are made to the original file. Other programs such as Photoshop overwrite your original file with a new file of the same name unless you choose to SAVE AS to preserve the original file. One built in advantage of shooting RAW is that the file must be converted to a different format before it can be edited in many programs. This will leave the original RAW file intact and all changes will be made to the “converted” file in a different format such as PSD, TIF, JPG and others. Lightroom allows you to work on the original file (RAW, TIF, JPG or many other formats) directly and have all of your edits in one place and at the same time keeps the original file intact, no matter what format it is. This allows you to apply different processing to the same original file, different crops, different color treatments, even generate a black and white treatment, all from one file in one workspace.
This brings me to the point of resizing for the web and watermarking your images. Because all of this processing in Lightroom is nondestructive, it is visible only in Lightroom until you EXPORT the file with the edits and processing that you wish to have on your final image. The most direct way of exporting is to PRINT your image. To print, you select the version of your processing that you wish to show in your print and when you choose PRINT, Lightroom EXPORTS your image to the printer, applying all of the edits and changes that you have made so that the printed image looks like the image that you see on the screen in Lightroom.
An image “printed” to the web is exported. This export process applies your edits to the web image so that the image will appear on your monitor as you wish for it to appear. This is an image that I watermarked for our Desoto Camera Club.
To read or download the complete tutorial as a PDF, click LR – Export, Resize, Watermark for the Web