Rule 9.3 - Thou shalt not harass people who don't want to PK with you
If the player you wish to kill does not want to play pk with you, you must leave them alone. While this seems obvious, PK players will occasionally harass non-PK players in an attempt to goad them into doing something dumb. Harassment is harassment, and it is strongly recommended that if your potential target doesn't want to play you should leave them alone.