Rosalie is the French diminutive of Rose — from the Latin rosa. Saint Rosalia of Palermo (1130-1166) is the patron saint of Sicily, where her feast day on September 4 is a major celebration.
Rosalie entered the U.S. top 1000 in 1881 and has been continuously used since. It is rising now — the broader return of long classical names with flower roots (Rosalie, Rosalind, Marigold, Magnolia) has brought it back. Today it sits in the U.S. top 200.
Rosalie does not currently appear in the US Social Security Administration's top 1,000 girls' names, so we don't publish a US rank or birth count for it. That says nothing about the name's standing elsewhere in the world — only that it sits outside the ranked US data we rely on.
In Pythagorean numerology the letters of Rosalie reduce to 7, The Seeker. This is a traditional interpretive system, not a factual claim about the name.