Thanks to Scott Sheppard at Autodesk for putting me on the right track.
This will allow Design Review users to create a Symbol in Design Review that contains their professional seal and signature.
You have two methods that you can use to create the seal.
Option 1: Creating the seal using a scanned raster image
Get a clean sheet of white paper, get a good load of ink on your stamp, and place your seal on the paper. Have the engineer sign the stamp example with a color pen of a different color than then ink used for the stamp. Scan the image.
In an image editing program, remove the white area with the Magic wand tool and make the image transparent as much as possible. Save the image in PNG format, a high-quality format that allows transparency.
Import the image into AutoCAD, and ensure that the image is scaled to the size of the original on-paper seal; set your units to ensure that you've got this worked out. Use the Transparency command and turn On transparency. The image should appear transparent. Set Imageframe to 0 or 2 so the border around the image won't appear when you print to DWF. Use the Plot command, and print the image to a DWF file.
Option 2: Creating the seal in AutoCAD
If you like, you can draw up the graphics of the seal in AutoCAD (again, at the same size as the actual physical stamp). Import the signature of the professional using the method described above. Plot the combined seal and signature to DWF.
Creating the Symbol for the seal in Design Review
Find the Symbol tool and click the drop-down for Create Catalog. Navigate to where you saved your DWF with seal and signature in it. Choose the Import each sheet as a Symbol option.
You have now created a symbol you can place on each page that contains your professional seal
To place your professional seal, click the Symbol tool and place the symbol on each sheet. You must do this for every sheet.