So all He lights on my k100 dim and brighten dependent on the speed of my engine..is this a for sure sign of a bad rectifier ?

This could be a sign that your starter brushes are worn or that your stater commutator is very dirty.  The starter acts as a ground path for the load shed relay's control circuit.  If you have certain starter problems the load shed relay will chatter while the bike is running.  The load shed relay controls power to the headlight.  While it is chattering the headlight will either cut completely off or dim.  Have you had any starter problems where the starter would not spin?  That is one sign.

Try checking the voltage at the battery when the problem is happening.  If the voltage is basically steady then I wouldn't suspect the voltage regulator.

Ok so pretty much the normal procedure to check the regulator ?thanls !