Please follow the below instruction to prepare your rescue media for use with the Ethernet port on your Surface Pro 3 dock.
Click on Download and select “Surface Gigabit Ethernet Adapter.zip”
Right click on the downloaded .zip file and select Extract All
Extract the contents of Surface Gigabit Ethernet Adapter.zip to
Rebuild Rescue Media
When you boot into Windows PE the network adapter should be detected.
Extract the contents of Surface Gigabit Ethernet Adapter.zip to the rescue media USB drive.
Within Windows PE open a command prompt and navigate using "CD" to the folder on your USB drive that contains the drivers.
Type drvload msu30x64w8a.inf and press return.
Your network adapter should now be detected.