Hi. I'm Dr. Lee and will do my best to help.
With an 8 oz kitten, which is half a pound, she should be intaking at least 1-2 oz of food a day. However, something I am VERY concern about is that, a 4-6 weeks old kitten should not be only 8 oz. If she is truly 4-6 weeks old, then she is severely malnourished or there are some severe liver disease going on preventing her from getting nutrients. If you are unsure of her age, and she is really only 8 oz, then she should NOT be on regular can food yet, as her true age is probably more like 2-3 weeks old, and kittens at that age should be on milk, preferably milk from the mother.
Please let me know if you have any questions or concerns. Thanks.