I need to split the RST line in two directions and also connect it to the opposite layer of the board.
I did it like this:
Is branching the RST line the right decision?
It is probably fine for this application, I've done this a few times. The few nH's of inductance and mΩ's of resistance that the vias add will not affect the rise times of the reset line for most parts.
If you're worried about the rise times in nanoseconds or if the RST line is impedance controlled, then you might have to worry about adding vias, the most likely situation is that you don't and adding the vias and a long trace is fine.
The best thing to do is calculate what the resistance and inductance of the vias and trace is with a PCB calculator and see if that affects the design at all.