4XL Rain Jacket - Where to buy?

Hi all, my first post here so play nice please
I looking to purchase a good quality rain jacket to replace my 10 year old gortex. Unfortualty, some expansion of my waist region mean I need approx 4XL jacket, but local stores only seem to go up to 2XL. Guess I will have to order on line, probably from the USA? How to confirm correct sizing when ordering a jacket online? Suggestions/help please.
Cheers, Rob

I looking to purchase a good quality rain jacket to replace my 10 year old gortex. Unfortualty, some expansion of my waist region mean I need approx 4XL jacket, but local stores only seem to go up to 2XL. Guess I will have to order on line, probably from the USA? How to confirm correct sizing when ordering a jacket online? Suggestions/help please.
Cheers, Rob