Hi,
I had the same problem, resolved it by doing the following:
1) Create your 167 pixels icon (PNG File) using any photo-editing software (I use Photoshop)
2) From XCODE, goto your project,
3) Open "Images.xcassets" this should display all your icons with the empty frame showing no image for the PRO device.
4) Select the Attribute Inspector from the right-hand-menu (this is the top right icon that looks like a hammer drill, i.e. an almost-square pointing down with)
5) This should display your "AppIcon" name,
6) Select the -> arrow next to it, this should open up all the images in Finder
7) Manually copy the file (from step-1) into this folder.
8) Go back into XCODE, you should now see the new image under "Un-Assigned" images
9) Drag the image into the PRO/Icon box, it should register there.
Good luck, let me know how it goes
Cheers
Heider Sati