I'm not really sure what rules you're referring to but adding honey at flame out shouldn't cause any issues. The wort is boiling when you stir it in.
That's a resonable amount for one gallon of beerr. I've used a pound of honey in a 5 gallon recipe.
Why do you think it's not going to turn out well? What are you trying to accomplish by adding honey?
If you're looking for sweetness or honey flavor you won't really get it from adding honey to the kettle. The simple sugars will be some of the first consumed by your yeast during fermentation. The alcohol created will have a drying effect on your beer rather than imparting flavor.
Some brewers believe that highly aromatic honeys impart flavors but that's contributed by the flower the bees collected the nectar from.
If you're looking for honey taste in the finished beer something like a honey malt might give you more flavor.