An intensive or reflexive pronoun is the two identical pronouns but differs in their function. Intensive pronouns are used to lay emphasis on the antecedent or the subject in the sentence. Intensive pronouns end with "selves" or "self". For example yourself, myself, themselves and so on.
Another way to identify the intensive pronoun in the sentence is by removing it from the sentence. Hence, if the sentence makes sense it is an intensive pronoun. On the other hand, if it doesn't make sense it is a reflexive pronoun.
Therefore, in the above passage sentence which uses intensive pronoun is,
"Ronnie herself walked up to him and ordered two lattes."
If the intensive pronoun 'herself' is removed, it still makes sense as:
Ronnie walked up to him and ordered two lattes.
