not trying to bulking up my muscle...

By tone, I'm assuming you mean you want to be able to see some muscle underneath the skin.

You can increase muscle definition just by losing fat, but it doesn't look like you have anything to lose.
You also *have* to increase the size of the muscle so it presses against the skin, creating a defined look. However, even as a male, you won't add very much...muscle growth doesn't happen that easily or quickly.

You can add size any way you like--heavy weight or light weight--by bringing your muscles to failure. This means you do so many reps, or the weight is so heavy, that you cannot perform another repetition. If you jog, it would be better for your sport to stick with higher repetitions so you can build some muscular endurance. It will increase the speed of your starts and finishes. So think in terms of 15-20 repetitions, reaching failure once you hit around 20. Squats and lunges are great jogging-related movements, and leg extensions and curls work well too.

If you only eat maintenance calories--what you need to maintain your weight after exercise--your growth will be very minimal. But it is necessary to increase muscle definition, especially when you don't have much body fat to lose.