Hi Kathleen, It sounds like you are digitizing plats over some aerial imagery. There are several ways to import the image from the pdf, but what I would suggest is saving the plat as an image, such as a .tiff or .jpg, once you have it saved in this format, which is essentially a raster, you can use the add data tool to import into your .mxd, then use the georeferencing tools to rectify the image to the ortho-imagery. Check out the following link for more help ArcGIS Help 10.1
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