Many times, this expression used after an already stated quantity (usually a small one) to further emphasize the unlikelihood of something by using hyperbole.
Other times, to refer simply to a noun.
Examples:
Sally is only able to have two of those candies, if any (at all).
I don't think I've ever had more than three conversations with him, if any (at all).
Her feelings, if any, were not shown.
-It is used as a continuation to an already mentioned noun - and, in so doing, it takes the same verb associated with that noun
Examples (based on the above sentences):
Sally is able to have two of those candies, if (She is able to have) any.
I don't think I've ever had more than three conversations with him, if (I've had) any (with him).
Her feelings. If (she has) any (at all), were not shown.
Hope this helps!