Calibration - different chessboard - YML file

Hi,

I can use the OfxCv "example-ar" with the chessboard made by cornersX=10 and cornersY=7.

How Can I change the the YML file in order to use a different chessboards, for example:
cornersX=5 and cornersY=4

or

cornersX=4 and cornersY=4

I do not know how to write/modify the .yml file parameters.

tks,

Pippo