Ordinarily, in case some of these calls cause process termination, randcall forks before making each call. This can be slow, so the -f option can be used to suppress this behavior.
The -c count option tells randcall to make count iterations through the list of calls it's using. (It always goes through the list sequentially.) The default count is 100.
The -r seed option allows one to set the pseudorandom seed used by randcall to generate the call arguments. The default seed is 0.
randcall prints what it's doing, so if it blows up you should be able to see what happened.
The system calls that do not take arguments are not on any of the call lists. Neither is reboot, to prevent accidental system shutdown.