Lightroom is great... I use it myself. It can add watermarks to your images, will scale them smaller or larger for different size images, etc. But I believe you will find it a little limited creating the image to be used as the watermark.
A freebie I have used for watermarks and many other things is Faststone Photo Resizer. This is designed for batch processing and, as the name implies, can make smaller copies of an image. It also can rename, make thumbnails, add borders and other effects.
But, once again, you have to create the image for the watermark somewhere. And, one limitation with Faststone when I was using it was that it couldn't scale the artwork. Maybe it has changed now, but when I used it I had to create watermarks specific for different final sizes of images.
If you actually want to use your signature, you could scan it, then use some editing program to drop out the background and save it as a PNG file. (A JPEG won't work because it can't have a "transparent" background). If you type set a "signature", you also have to save it as a PNG for it to work (there may be other file type that will work, but I'm unaware of them). I use Photoshop to create my watermarks. But I bet there are many other programs... perhaps even Paint, which you already have if you are a Windows user.
You also might look into Adobe Elements... I am not certain how much it can do because I use Photoshop along with Lightroom. But each version of Elements has added more an more capabilities, so I wouldn't be surprised if it can do watermarks, too.
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Alan Myers
San Jose, Calif., USA
"Walk softly and carry a big lens."
GEAR: 5DII, 7D(x2), 50D(x3), some other cameras, various lenses & accessories
FLICKR & PRINTROOM
