Something is cooking...

[guohua]

Mr. G. Here.
YES!
This would have been my choice of Contact Areas.
A Museum or Public Bathroom is better than a Restaurant.
In a restaurant, I've noticed that someone is always looking or watching people coming and going.
You'd have to have paid for your meal (cash) and then made contact with your victim before leaving, that is Awkward, because if you trip your victim or brush against them ruffly, someone will take notice and stare.
Also, most cash registers have cameras, not an ideal place.

A jogging area or dog park, crowded street while window shopping even a newspaper or magazine stand.

So the 'door-handle' is not a good idea, then! Which -when protecting a spy, would probably be on cctv.
The notion of a perfume spray seems ridiculous too.

CCTV, that is now (not in my day) on every corner in the EU/UK I understand.
So, with cctv cameras possible on the street picturing the movement of peoples in more than one direction, the door-knob/door-handle is not a good idea if you want to stay in the shadows and unknown.

The Perfume Spray is an Effective Means of Poisoning your Target if it's a Female, How do you know how often she wears this Perfume? But then How do you get the Poison in the Perfume Bottle, there is the problem, you'd have to actually enter their home and be seen by How Many Cameras?
 
Remember, Stealth and staying in the Shadow and not in the Light is your best option for a Successful Operation and Survival.
So, I'd watch my target and study my target, get to know every aspect of the daily movements and who they met with and when and where.
Who's around them, does he/she have their own stealthy security?

Plan to my contact in a Very Public place if possible away from cctv and children. Yes, children get in the way, under your feet as you make your escape.
Remember, the target is not going to fall ill there and then, No, they well not know for a few hours or 30 to 40 minutes.
Unless you use a Nerve Agent and they inhale it into their Lungs, they will immediately be affected and start to choke and cough and vomit.

Sorry, I was a little Long on my answer.
The short answer, one round center mass from 900 yards.
Your target will be dead before the sound of the shot is heard and you can dismantle your weapon and store it away and walk to your vehicle and drive away.