How to crimp Molex connectors for low voltage, threshold, big pad, for the ARGO-YBJ  RPC
 

View of tool and pin
Insert pin this way
Insert wire into the pin with the plastic cover too and press the tool until release
View of Molex connector (2 pins type), look at the round side of the holes
Insert pin into the plastic case, pay attention to previous point
Help yourself by pushing with a little screwdriver until stop
Easy final result