To match a donation on GoFundMe Charity, the company or donor matching the donation can place a second donation to the same fundraiser for the same amount. They also have the ability to leave a comment during the donation process saying something like "This donation is a match for NAME's donation of $$$” in order to clarify your match.
However, every person and/or company’s matching program is unique and may have additional requirements that have to be met. We’d recommend reaching out to the company providing the match to find out what their specific requirements are for a matching gift.