in the pocket guide it states that a Profession skill check allows you to earn 100cr times skill roll result for one weeks work, i.e.: is my Earth Force Lieutenant is third level and has the skill Profession (Military) +4 and rolls a 9 he would earn 1,300 credits that week, the next week he rolls a 17 and earns 2,100 credits. the skill also says that untrained laborers can earn 25 credits per day