  The general boundary formulation of quantum field theory is applied to a
massive scalar field in two dimensional Rindler space. The field is quantized
according to both the Schr\"odinger-Feynman quantization prescription and the
holomorphic one in two different spacetime regions: a region bounded by two
Cauchy surfaces and a region bounded by one timelike curve. An isomorphism is
constructed between the Hilbert spaces associated with these two boundaries.
This isomorphism preserves the probabilities that can be extracted from the
free and the interacting quantum field theories, proving the equivalence of the
S-matrices defined in the two settings, when both apply.
