While Edwins's answer is excellent, and not in debate (especially the observation that these whotsits are inconsistently analysed), I would like to offer another tool for analysing them.
At least one definition of a phrasal verb includes the fact that it is an idomatic phrase.
So in deciding whether a phrase is a phrasal verb, ask yourself "is the actual meaning of the verb being used literally?". If so, it is not a phrasal verb, it's probably a verb plus preposition. If the literal meaning of the verb does not really apply, and the meaning of the phrase is idiomatic, then its a phrasal verb.
So for example in "Seeing her ex makes her break down and cry", "break down" is a phrasal verb. Nothing is literally breaking, and the direction down is not really relevant. The phrasal verb has an idiomatic meaning.
In contrast, "rub on" is not idiomatic. You are rubbing something onto something. It's pretty literal, and the meaning of "rub" is its normal meaning.
Sentences like "You should rub on some lotion" are contractions that make the a phrase appear to be a phrasal verb. But they aren't (IMHO). This sentence structure arises from
1) Implying rather than stating the target of the action.
"You should rub some lotion on yourself"
"You should rub some lotion on" (obviously, yourself)
2) Rearranging to avoid a dangling preposition
"You should rub on some lotion".
As Edwin says, this is tricky one, and you could make an argument that "rub on" is a phrasal verb that means "rub on yourself". Personally, I would not readily accept this argument. It is much more like a contraction than a phrasal verb, because it is not really idiomatic.