France is officially referred to as the Republique Française, hence the use of the "RF" monogram, as a sort of logo (though France has had a proper official government logo since 1999).
The RF cypher appears on the unofficial Frech coat of arms (properly an acheivement of arms) shown on the left along with fasces in the background.
It also appears on the form of pseudo-arms depicted on the right, along with French tricolore flags and the fasces once again in the background.
It also appears on coins and stamps, along with other national symbols - eg the French cockerel or rooster on the stamp, Marianne on the coin.
The French national cypher is one of the gererally recognised symbols of sovereignty not mentioned in article 2 of the French Constitution of 1958, which refers only to le drapeau tricolore, bleu, blanc, rouge: The French Flag , L'hymne national, the national anthem, The Marseillaise and La devise de la République; the motto . "Liberté, Égalité, Fraternité".