Jack Burkman, a GOP lobbyist who has been following the case for more than a year, is behind the ad.
Fox News is fighting a lawsuit that alleges serious violations by one of its journalists.
Fox News is accused of working with the Trump administration to use the DNC staffer's murder as public relations spin.
The president is alleged to have specifically reviewed drafts of the story and made editorial changes.
"Please cease using Seth as a political football in predetermined partisan narratives,” the family said.
Only in a society lacking civic faith could so many people believe that a young man was murdered for forwarding what turned out to be embarrassing work emails.
Sean Hannity continues to insist that DNC staffer Seth Rich was murdered because he'd leaked information to Wikileaks.
The internet entrepreneur, who is fighting extradition to the U.S., claims Rich contacted him as early as 2014 and was involved in the DNC leaks.
A tweet from the embassy comes days after a report that suggested Rich was a WikiLeaks informant, which has since been refuted.
Citing an unnamed “federal investigator,” a Fox News report suggested that Rich gave 44,000 Democratic National Committee emails to WikiLeaks.
GoFundMe page sets a $10,000 goal to help raise awareness and lead to information that can solve the murder.