xrandr question

[Bill Vance]

Running Kubuntu 16.04 here.

I'm told that if you want xrandr to do a particular resolution
on boot up, you have to put the command in a file named,
".xprofile".  That's nice as far as it goes, but where do I put
the file?  Does it need any special treatment like:

    chmod a+rwx ~/.xprofile

or whatever?

Bill