I want to give my one month old some formula how should i go about it?

i decided i want to give my 4 week old daughter a bottle of formula once a day i have simalic sensitive and enfamile premium light, i have given her a bottle of both in the past that she projectile vomited both up. whats a good brand or way to give her one bottle of formula so that she doesn't throw it up? can i mix my milk with the formula?