Hello LMZ,
A question similar to yours has been discussed in this previous thread. As discussed there, you will have to list all the emitted VOC species towards which you would like to calculate FORM sensitivity.
For example, if your emitted VOC species are AACD, ALD2, MEOH, FACD, ALDX, and ETHA (this very likely is an incomplete list, you will have to check your emission files) and you would like to calculated FORM sensitivity towards those species, you could define a “EVC” group as follows:
EVC
EMIS
GRIDDED_EMIS
SPECIES
AACD, ALD2, MEOH, FACD, ALDX, ETHA
In your ASENS output file you should then see FORM_EVC (among other species) which would be the sensitivity of FORM towards emissions of the (VOC) species included in the EVC definition. As noted above, the full list of your emitted VOC species is likely much longer, and as also noted by Sergey in the thread linked above, the exact definition of “VOC” for your analysis is something you will have to decide on.
Also, please do not post the same question in multiple threads as it introduces unnecessary clutter to the forum.