WeFulFillIT has the capability to add your logo to the top left corner of the packing slip that your customer will receive with their shipment.
To have your logo added to your packing slips you will need to email the logo as a .jpg file to customercare2@wefulfillit.com. The .jpg file must be formatted properly or it will not show correctly on the packing slips. 
The Logo .jpg must be formatted as follows:
Resampling: Best Quality
By absolute size and Maintain aspect ratio
Pixel size
Print Size