I recommend to use the RIG-I antibody kit from Cell Signaling (https://www.cellsignal.com/products/primary-antibodies/rig-i-pathway-antibody-sampler-kit/8348).
Stimulate the RIG-I pathway by 5'pppRNA (synthetic ligand of RIG-I, Invivogen) transfected with some of the cationic reagents (LyoVec or Lipofectamine).