To young to learn just yet   and if it is a medical problem   than you are
causing a problem

When a cat is doing it on purpose than it can be used but right now it could
be medical not behavioral plus the age of the kitten

IMO when it gets a little older there are better methods than the squirt
bottle such as marbles in a coffee can.  If I used a squirt bottle on Rumble
I would be dealing with a nasty response where I sleep Rumble and a few
other of my cats could care less if you squirted them.  they would get
revenge if daddy was mean but they hate the coffee can

Water is used for issues such as getting on counters NOT for litter
training.  You are accomplishing nothing by squirting her where she pees on
the floor if you continue she will start hiding and peeing in other places.

Celeste

Confinement is a very good starting point.

The reason that it would be best not to use water is because she might
associate the water with when she needs to go to the litter box.
Should this be the case, then she will consciously try to hide away
from you when she feels the need to use her litter box, (or where ever
she is choosing to go right now. A second litter box is an excellent
idea right now. It will give her the confidence to use it).
Explore the possibility that there might be something medically wrong,
by taking her to see your vet 1st. It is entirely possible that this
is not a social issue.

Another trick that I have found useful when I have kittens come in
that don't seem to be using a litter box properly, is to add a small
amount of urine soaked litter, to mix in with your chosen litter. As
soon as the kitten smells this, they seem to associate the fact that
this is where it is appropriate to go. I can't stress how important it
is to use a very small amount of litter you can mix in, or that it
must come from a female cat whom you are sure has no other medical
problems@ all!. With a 10x stronger sense of smell, kitty will be able
to recognise that smell, where you might not be able to.

Normally, a mother cat will teach her kittens where it is appropriate
to use the facilities, but if she came to you as a barn cat, then she
has no idea where it is that you are asking her to go, because barn
cats would be used to going outside.
This might take a little while, & a lot of patience to sort this out,
however, as long as she is somewhere, where it is possible to simply
wipe the floor down, then it doesn't really matter for a short while.

Best of Luck,
S;o)