The phrase "a foil of" is correct and usable in written English.
It can be used to describe a character or element that contrasts with another, highlighting particular qualities or traits.
Example: "In the novel, the protagonist's best friend serves as a foil of his character, emphasizing his more serious nature."
Alternatives: "a contrast to" or "a counterpoint to".
"It has not been a pleasant thing for any of us to watch," said Jim Courier, a foil of Sampras's in the 1990's.
Though Mr. Romney frequently makes Europe a foil of his domestic stump speech, warning voters that they do not want to head down a path to becoming a "social welfare state," Mr. Romney praised Poland as an example of a nation on the rise.
And there is the creepy, paternal psychiatrist (Mitch Tebo) to whom Annabell increasingly transfers her unhealthy filial dependence; he is a foil of the one decent person (and other parental substitute) in her life, the Neiman saleslady (Lee Roy Rogers) who has waited upon Annabell for decades.
Mr. Nonas said his design, a narrow green rectangle bordered by historical text and granite and wood benches, will be a "foil of quiet to the strange chaos" of the surrounding space, which has five elevated train tracks and 10 lanes of traffic.
The electrochemical behaviour of such platinum electrodes has been assessed and compared to a foil of platinum.
A foil of α-Fe was used for calibrating the velocity scale of the spectrometer and as a reference of isomer shift.
Miaow, fetch the lovely lady a foil pouch of Sheba!
In response to the obvious question ("Couldn't I make a foil pouch?"), of course you could.
Rather than sell us the whole box, he pulled out a foil sheet of pills and handed it to us. .
It is a good idea to include a foil type of emergency blanket.
"He still plays a game that other guys don't," said ANDRE AGASSI, a longtime foil of Rafter, who is a pure serve-and-volley player.
