retardation factor, R F in planar chromatography, in column chromatography

https://dx.doi.org/10.1351/goldbook.R05353
Ratio of the distance travelled by the centre of the spot to the distance simultaneously travelled by the mobile phase:
R F = b a
By definition the R F values are always less than unity. They are usually given to two decimal places. In order to simplify this presentation the h R F values may be used: they correspond to the R F values multiplied by 100. Ideally, R F values are identical to the R values used in column chromatography.
Source:
PAC, 1993, 65, 819 (Nomenclature for chromatography (IUPAC Recommendations 1993)) on page 845