How can I make the icon of a folder to be a given .icns file? I have a .icns file.
I want to make the icon of folder to be this .icns.

How can I make that?



EDIT

The .icns file that I use does not have the .icns file as its icon. 

I have tried to copy the .icns file in Preview and paste it to the icon, but it copies the 1024x1024 image.
"Get Info" of the folder you want the icon to be replaced,
using Finder, drag and drop the *.icns file to the current top, i.e. smaller icon of the folder in the "Get Info" window.