Coolant leaking from gasket, coolant seal?

Hi there, I recently had someone take a look at my vehicle to see where my coolant was leaking from. We saw it came from a sort of gasket; it didn’t seem like a big leak. The only solution for me financially was for me to buy a coolant seal called K-Seal. I haven’t used it yet because I am afraid it will do more damage. Is it safe to use, and will it fix the gasket crack?