The phrase "capacity with" is correct and usable in written English.
It is used to describe an ability or aptitude to do something. For example: "The student has a great capacity with mathematics."
Where were you during your supervisory capacity with Father Geoghan?
The bus was then quickly stuffed to capacity with riders, meaning yet another uncomfortable ride home.
The centre was overcrowded – at double its intended capacity – with new arrivals.
But don't kill Fido and don't kill anyone associated in any capacity with Mary Poppins.
Instead, he said, "We've increased our raw capacity with new buildings".
As does the notion of replacing existing capacity with available renewable technologies.
The lobby was already filled to capacity with scavvies marking their territory with loud cheers.
Around him are towering shelves, packed to capacity with plastic-wrapped albums.
At Global Crossing, the company traded capacity with other fiber optics companies.
(It can also be used while the person still has capacity, with their permission).
Mallinder has previously worked in a coaching capacity with England Saxons and England Under-21s.
