>> "Do I expose myself to fluoride because of that or it won't hurt through skin?" <<
Yes, you expose yourself if your water is fluoridated.
There are shower filters that can reduce the fluoride about 50% or so... though not entirely.
Your unasked question answered...
Is it harmful?
That depends on whether you have a strong, balanced, terrain (mineral nutritional profile).
That said, repeated exposure over time, without attention to excellent nutrition (junk food diet) can degrade your "terrain" and lead to illness.