Outside ski dominant, but you need to be able to pressure your inside ski as well. No formula for it, but maybe averaging around 80%/20%, at times possibly closer to 60/40, but not a big issue at Level 1.
Just make sure that your inside ski stays on the snow.
Have you read the Alpine Exam Guide for your division? That has the information that you need to prepare and should answer your question. Also talk to individuals that have taken the exam and your SSD.
My observation is that most successful level 1 candidates do not make parallel turns with 100% of their weight on their outside ski. My opinion is that all level 1 exams will not require skiing parallel turns with either 100% of their weight on the outside ski or 50% of weight on each ski (unless the exam is done under extreme powder conditions). The ability to either control weight distribution (to set any percentage of weight on either ski at any point in the turn) or let weight distribution be controlled by turn forces is a skill level that is not required for level 1 cert, but it will help a candidate exceed the required standards.