Import from excel to create a dado in a gable rectangle

I have a rectangle with the X and Y coordinate of 200/200 and I need to place a through dado to be X =192 and 176, (16 units wide) and have Y being -3/+203 so that the tool goes full length. In exporting from excel, what is the dado information I must import into RHINO? The information will be saved as DXF for use by Mastercam which requires the four points of the dado to be connected with lines. Thanks for your asssitance as I am a brand new user.