Display Mode: Choose Best Fit or Stretch. The other options are useless.
Dimensions: Make the dimensions exactly the same size as your image. You cannot use the bitmap control to resize the image.
How to determine the exact dimensions - images are normally defined in pixels; use this resource to determine the inches for the bitmap control Assume 96DPI where asked.
Next and most important (if you want images to look their best) is to set the PDF Options where you call the report. See image below, set the JPEG Image Quality to High or No Compression.
