Hi David,
I do not know what the 'RS' stands for.
Flash.S 25-40 2C or 40 4C Don't know why it is '.S', but that's the way it appears in the catalog
Flash 45-50 2C or 48-53 4C
Flash RS 60-91 2C or 80-90 4C

Citation 45
Citation 60

Dash Five 120 120 4c (I don't know the exact nomenclature for this kit; I have seen an ad in a Japanese R/C magazine for this airplane; so it did exist!!)
Dash Five 60 2c or 80-120 4c
Dash Five 45
Dash 25

Sensation 2000 120 2c or 4c
Sensation RS 60-108 2c or 90-120 4c
Sensation 1400 32-60 2c or 40-70 4c
Sensation 1400 ARF