  We have considered the critical Casimir force on a $^4$He film below and
above the bulk $\lambda$ point. We have explored the role of fluctuations
around the mean field theory in a perturbative manner, and have substantially
improved the mean field result of Zandi et al [Phys. Rev. E {\bf 76}, 030601(R)
(2007)]. The Casimir scaling function obtained by us approaches a universal
constant ($-\frac{\zeta(3)}{8\pi}$) for $T\lesssim 2.13~\text{K}$.
