Nikon D6 Reference Manual page 1024

If you chose [Select folder]:
• Highlight a folder and press J to select; all pictures in the
selected folder will be copied at the size selected in Step 3.
7
Save the resized copies.
A confirmation dialog will be
displayed; highlight [Yes] and press
J to save the resized copies.
D
Resize
Depending on the copy size, playback zoom may not be available
when resized copies are displayed.
972 N The Retouch Menu: Creating Retouched Copies