A search on "Touchhole size" results in much info.
The touchhole location should be centered on the pan horizontally, and even with or maybe just a bit above the top surface of the pan vertically. If you look at the edge of the pan from the side, the touchhole should look like the setting sun just touching the horizon.
Size? You should be fine with 1/16". Chambers WL liner is .055" IIRC, but is coned inside.
-Ron