The first thing to say is that this is a surprisingly tricky question, the answer to which is far more obscure than you might imagine. In rugby union, kicking duties – which, of course, include penalties, conversions and drop goals – often, but not always, fall to the fly half. Indeed, it is no coincidence that the top ten highest points scorers in the history of Tier 1 international rugby union, which includes England, France, Italy, Ireland, Scotland Wales, Argentina, Australia, New Zealand and South Africa, all wore the No. 10 shirt.
Of the aforementioned tensome, Englishman Johnny Wilkinson, Argentine Diego Dominguez, who played most of his international career for Italy, and Irishman Ronan O’Gara all feature in the top ten for career drop goals, with 36, 20 and 15, respectively. However, while it might seem reasonable to use this trio as the basis for further investigation, it turns out that the record for the most drop goals in a rugby union international belongs to none of them, nor anyone else in either top ten.
The most drop goals kicked by an individual in a Tier 1 rugby union international is five, scored by South African fly half Jannie de Beer in the second half of a Rugby World Cup quarter-final match against England at Stade de France, Paris on October 24, 1999. However, according to Guinness World Records, the most drop goals kicked in any rugby union international was six, scored by Russian fly half Konstantin Rachkov against Spain in a European Nations Cup, a.k.a. Six Nations B, match in Inca, Mallorca on February 16, 2003. The European Nations Cup featured Tier 2 and Tier 3 rugby nations.