Can’t tell for the Romantic Manifesto, but in Atlas Shrugged, Ayn Rand uses the word “value” as a synonym of “rule of conduct”. For example, she argue that “rational evaluation” is a correct value for man in the same way that “flying” is a correct value for birds.

She calls her philosophy objectivism because the thinks that correct values, which means rules of conduct that leads to environmental fitness (in her words says : “survival”), are objective.