Yes, 2 tsp twice a day just like in the article.
I would not vomit her.
Make her normal feed and plenty of fresh water available free choice during waking hours.
Coconut oil is what I prefer, it can be hardened in the fridge and most hens will eat tiny chunks on their own. Olive oil if syringed and aspirated can cause lipoid pneumonia.
A crop will feel full(ish) with water/food, etc. during the day when the hen has been eating/drinking, this is why it's best to check crop function first thing in the morning before they eat/drink.
https://www.backyardchickens.com/ar...w-to-know-which-one-youre-dealing-with.73607/
Fenbendazole (Safeguard) is dosed by weight, not pea size. Dose her at a rate of 0.23ml per pound of weight given orally once a day for 5 days in a row if you are wanting to deworm her.
I highly recommend that you read the article I linked all the way through, including the comments section. There's a lot of very good information found there.
I hope your hen feels better soon.