MEGA 2560 R3 12v and reset pin question

Noob question… I'm using 12-13.5 V input to run a Mega, and I have read some postings that have given me conflicting information about how to properly set up the reset pin. It seems that there is an internal resistor in the reset pin circuit, but I had read that a current limiting resistor is sometimes necessary (although mostly in reference to the 328 chips). Some of the older information on reset pin and resistors seems to be limited to the older boards (pre- R3s), so I suspect it should be ok to directly ground the reset pin, but I'm looking for more current info from someone who knows.

The circuit powering the Mega is a 12V SLA battery that is being charged and can show 13.5 V when on charge (but that seems to be within the operating limits).

I need to connect the reset pin to a switch to ground, and can not find clear information on whether there is a problem with doing so with a 13.5 v input to the V-in pin or through the barrel jack. I saw a post which said that the V-in pin does not go through a diode in the DC power jack circuit, but I don't know if this matters to my reset pin question. As I understand it, the diode is for reverse voltage protection.

Thx.

When you press the Reset button, you are connecting the Reset pin on the Power header to Gnd.
You can use an external switch to connect the Reset pin to the Arduino Gnd also.