From Path of the Vampire Wiki
Proficiencies will be used mainly in quests when they are available (though possibly quite rarely), but also in certain roleplay threads and live chats, if the thread initiator decides. They deal mainly with what experience your character has had in specific fields. There is a certain amount of necessary overlap between the proficiencies (medicine and chemistry for example), but don't worry, a good quest writer / GM will take those overlaps into account where possible.
Everyone starts with 10 free proficiency upgrades which can be used to increase any proficiency from 1 to 4 stars, but not 5. Once those free points are used, RPP and/or Karma will be necessary to increase proficiency. You cannot upgrade a proficiency beyond a certain point, if you have a low key attribute in that area. Different proficiencies require different stats: Knowledges (academic) require intelligence, Skills require skill, and Etiquettes require charisma.
Below you will find an overview of proficiency stars, their cost, their limits, and the key stat required to attain a certain level.
You have a great deal of knowledge and experience with the subject. You could teach the subject in a university if you were required, and are considered an expert on the matter.
Cost: 8000 RPP or 3 karma
Prerequisite: Key stat of at least 18.
You are considered by many as one of the leading experts on the subject alive today. Your knowledge might not cover every single facet of this subject, but it comes quite close.
Cost: 9000 RPP (cannot be bought with karma)
Prerequisite: Key stat of at least 23.
Your name would likely come up in a list of 50 people who were the absolute best at this subject, living or dead, if you were one for publicity.
Cost: 10000 RPP (cannot be bought with Karma or free upgrades)
Prerequisite: Key stat of at least 28.