To figure out which ReaxFF potential file is suitable for your system is your job not mine. Every potential file has an associated publication and that publication describes what the parameter set what trained for. The file name in your screenshot (very, very bad idea to use those, BTW) suggests that it may be the force field for combustion reactions between CO, H2O, CO2, HCHO, HCOOH, and so on. That would most certainly not be suitable to represent bulk water at 300K. In fact, a good benchmark for the force field would be to run a simulation of pure bulk water and compare the structure (e.g. g(r) for O-O, O-H, and H-H) to those for well known and tested water potentials (e.g. TIP3P, SPC/E, TIP4P) and experimental data.
You are not getting the point and it also seems, that your knowledge of ReaxFF and how to use it is insufficient. So my suggestion is to study that first and do not try to run simulations with models and methods that you are lacking insight into. You are very likely to make (very) bad choices and get bogus results.