Allison, one of my favorite daily reads, posted a blogging tip a while ago on how to add your signature automatically. If you're looking for just a signature, follow her instructions. They're simple and easy to follow.
If you want your signature to be a link - like to your own Executive Homemaker store, for example. First make your using Allison's tutorial and then follow these instructions:
For Blogger, edit your Layout and click the Settings and then Formatting tab. Scroll down to the bottom where you'll find Post Template.
Type in the code above. You'll need to copy/paste the link of your store, and then the direct link of the picture from Photobucket (or what ever website you used).
This is what it will look like! (see below)