The integral equation defined on a finite interval with convolution kernel, which is the basic equation in the analytical kinetic theory of neutrals in a bounded plasma slab, is solved by reinvestigating the corresponding Riemann boundary value problem. For the case that the Fourier transform of the kernel is a rational function, a general analytical solution formalism is derived and used to calculate the density of hydrogen neutrals, without numerical means, for the cases of homogeneous and inhomogeneous plasma temperatures.