None, zero, zilch, besides being useless, it contains
alcohol which can be lethal to a cat.

Here are some links to read about RR.

Use of Herbal Remedies to Control PetBehavior          S. Schwartz  
School of Veterinary Medicine, Tufts University, Massachusetts, USA
http://www.ivis.org/advances/Behavior_Houpt/schwartz/chapter_frm.asp?LA=1

Rescue Remedy®. This substance is marketed as a "natural reliever
of everyday stress...proven to be as helpful with animals as it is
with people". This claim is unfounded by published data.

Mystical Medical Alternativism
http://www.csicop.org/si/9509/alternativism.html

Bach flower therapy (Bach flower essence method, Bach flower essence
system):  Quasi-homeopathic system of pseudodiagnosis and
pseudotherapy.

Flower power: ALL IN THE MIND ?
http://www.healthwatch-uk.org/nlett40.html#bach

"Flower remedies are commonly divided into "type remedies" which
correspond to certain personality types and "mood remedies" which
correspond to certain emotional states. They are made by placing
freshly picked flowers in a bowl of spring water. The bowl is then
left in the sun for several hours. This process is believed to
"energise" the water. Subsequently the flower essence is preserved by
adding 50% brandy."

BarB