It would be best if you used mobility with respect to a standard compound. Rf, or mobility with respect to solvent front, is highly variable even in the same lab under similar conditions.

Yes I agree with Greg, for identification purposes using TLC, you should run the samples and standards on the same plate; if the compounds are not identical the Rfs should be not identical, but if the  compounds have identical Rfs, does not mean the compounds must be identical; different compounds could have identical Rfs, so it will be nice if the UV or MS of the spots can be measured for confirmation (using densitometer and MS spectrometer)

I agree as to the information regarding Rf values, but if you use a reagent to visualize the spots and the colors or shades differ from the standard sample you know at this point that the compounds differ.  If you have a UV light source with different frequencies, and the spots give similar results (and if the visualizing reagents give similar results than you need to run MS or GCMS or LCMS to get identifications.  If the results differ from what you thought, you should rerun the TLC or GC with the appropiate standards.

Dear Wayne, I use a special biosensor as mentioned in relevant reference, and other condition such as TLC plate, solvent are completely same with reference. In this situation it is not correct to use Rf values from reference??

The ideal situation would be to run on same plate at same time.  It is possible for different lots and plates in same lot to have slight differences that may affect Rf values.  If you have confidence in standard and the match is valid, then it should be okay .  I am a forensic scientist so I have a bit more sensitivity to slight variations than a research chemist, but you should still show that the match is valid each time you open a new box of plates.  An easy way to do this is once you have a pure substance as discussed above such as shown by GC, LC, MS, etc, save a portion of that material as secondary standard to use with TLC.  It will also show if degradations  occur under your conditions.