* "Kirsten": This is the closest spelling to the English pronunciation, but it's a Dutch name.
* "Christine": This is a common French name with a similar sound, but it changes the initial consonant.
* "Kerstin": This spelling is closer to the German pronunciation of "Kirsten," but it's not a traditional French name.
Ultimately, the best way to spell "Kyrstin" in French depends on what sounds you want to emphasize.