You can simply use it: open eclipse, load bench.pl via [bench]. and then state e.g. generate(10, 50, "fileprefix"). This example generates 10 programs with each 50 Atoms and saves them as fileprefix1.pl ... fileprefix10.pl.
The default parameters lead to mostly unsatisfiable logic programs. You may also change some parameters with set_pp/1, set_pn/1, set_d/1 or set_cs/1.
Warning: Some combinations of parameters, number of instances and number of atoms may lead to the message 'disk quota exceeded'.
Note: The prolog sources partially base upon the benchmark generator for ASP - Kathrin Konczak
Benchmarkgenerator: bench.tar.gz