  In this paper, we compute multiparticle form factors of local operators in 2d
$\phi^4$ theory using a recently proposed method [1] for efficiently
implementing the LSZ prescription with Hamiltonian Truncation methods, and we
adopt Lightcone Conformal Truncation (LCT) in particular for our calculations.
We perform various checks of our results at weak and strong coupling, and
elucidate the parametric behavior of truncation errors.
  This opens up the possibility to compute S-matrix in various strongly coupled
models using the LSZ method in LCT.
