From my experience:
You can fit about 15 drops of oil in a "0" capsule. You may combine several different oils into one capsule. To avoid risk of irritating the throat, esophagus or stomach, we only use up to 3 drops of essential oil in a capsule and fill the rest with a carrier, which should protect the esophagus and stomach and make the essential oil more bioavailable. Less many times is just as effective as more and carries less risk of harm.
Ask yourself: "Why do I need to take internally?
Unless otherwise noted on the detail page (e.g. Pennyroyal), our oils are suitable to be taken internally/orally with wisdom and understanding of safety issues involved with the specific oil. Typically 1-2 diluted drops is all that should be taken at a time, no more than 3 times daily, unless under the care of a health care provider who has experience with essential oil ingestion. We feel that in most cases, topical use or inhalation are the best methods to address issues.
I typically save oral use for flu or intestinal infections. Taking daily is not recommended especially if you have liver or kidney issues, as oral use may tax the organs. Otherwise, a few drops with a carrier oil is fine occasionally as needed. Start slowly and see how your system tolerates ingesting the oils.
The reason we prefer vegetarian caps is that they take a lot longer to break down. If we fill them carefully and don't have oil on the outside, we've had them last for several weeks in a dark jar.