Bottle feeding a weak kitten. Any tips?

My mothers cat has six kittens about three weeks ago. Today my mom noticed the runt was over in a corner and couldn't lift his head, wich is not normal because he was. I went over to take a look at it and the poor things is soooo skinny and isn't walking or moving much. It won't take a bottle so I am using a baby med dropper to force feed it. Any good tips? How often should I feed it? Is there anything it can eat or drink to make it gain weight? Any info would be helpful, I'm so worried he won't make it. Thanks!