The phrase "appearance in support of" is correct and usable in written English.
It can be used in legal or formal contexts when referring to someone's presence or testimony that backs up a claim or argument.
Example: "The witness made an appearance in support of the defendant during the trial."
Alternatives: "testimony in favor of" or "presence to support".
NBA hall-of-famer Charles Barkley made an illuminating appearance in support of Peterson on CBS.
It was financed by super-producer Megan Ellison, the daughter of Oracle corporation CEO Larry Ellison, who made her first press conference appearance in support of the film.
She stood in her New York hotel room, on her third or sixth or tenth visit to America, preparing to make another appearance in support of "The Deep End".
He recently made an appearance in support of Green Week presented by Sprint and the N.B.A. that featured a variety of activities to generate awareness and financing to protect the environment.
A bare two weeks after that, Walt Disney's Touchstone Pictures expects to release "The Hot Chick," a Happy Madison comedy in which Mr. Sandler puts in an appearance in support of his friend Rob Schneider, who portrays an attractive female teenager caught in the body of a not-so-attractive older man.
Making her first public appearance in support of a petition to stop the film from opening in Philippine theaters on July 7, Mrs. Marcos, the 74-year-old widow of the dictator Ferdinand E. Marcos, expressed hurt over what she said was the film's failure to show the couple in a serious light.
He accompanies his more-famous son, Prince Charles, and grandsons, Princes William and Harry, in processions and has made appearances in support of the British royal family and various charities.
N.H.L. Commissioner Gary Bettman, who has made several public appearances in support of Wang's Coliseum-related projects, reiterated his support on Tuesday.
The pleas were made during a week of legal argument at London's Snaresbrook Crown Court where the pop singer made two appearances in support of her husband.
May, who backed the prime minister's pro-remain stance in the referendum campaign but made few public appearances in support of the cause, hopes to be seen as a unity candidate to bridge the divide in the party.
