Congratulations on your new kitten!
At 9 weeks of age, kittens are particularly prone to injuries as they are inquisitive and active but lack balance and common sense.
There are many things that can cause non weight bearing lameness, including a grazed pad, broken claw, strained muscle, fracture, dislocation etc. and without examining her it is impossible to know exactly what is going on. Indeed, even with examining her it can sometimes be tricky (especially in young, wriggly kittens) and we sometimes have to take an X-ray.
I would check her pads, in between her toes and her claws to ensure all is normal. Then gently flex and extend each joint to ensure she tolerates this and it is not too painful. Look for any swelling, wounds or source of heat.
If she has twisted or strained herself, she should be able to put some weight on the limb and it should get gradually better and better as the hours pass. You may notice when she is happy/excited she seems to forget it hurts and walks on it quite well. Many strains will resolve with a few days of rest.
Speed up healing by encouraging rest and preventing her jumping on and off things or running about. I appreciate this is tricky at her age!
If, however, things are not improving over the next short while, she is not putting any weight at all on the leg or she herself seems unwell (lethargic/depressed/off her food etc) it would be best to have her assessed. She may well need some pain relief/anti-inflammatories.