[I believe this question already exists somewhere else on this website, but I can't for the life of me find it.]
In short, though the present tense is also possible, the most natural choice would probably be the past tense:
She touched me where my neck met my collarbone.
The main clause happened in the past, while the subordinate clause is a timeless fact; that is, it was true in the past and it is true now. Which tense to use in the subordinate clause? General rules about the sequence of tenses shouldn't normally be involved, since it is a timeless fact.
The most logical choice would be to use the present simple, because that is the common choice for timeless facts in a main clause (cf. mice like cheese, the Earth revolves around the sun, Liechtenstein borders on Austria, etc.). If I said "Liechtenstein bordered on Austria", you might expect to hear that the borders were changed later.
However, this is where assimilation or attraction of tenses kicks in: if a certain tense is used in the main clause of a sentence, especially a past tense, most writers will have a natural inclination to use this tense throughout the sentence where possible, because it looks neater in some subconscious way. (Note that this doesn't apply so much to tenses other than the past.)
In this case, since the subordinate clause is true now and was also true in the past, the simple past tense is possible; I'd say that either tense would be all right, but the past tense looks a bit more natural, especially in speech, where this attraction usually has an even stronger influence.
Fowler as edited by Burchfield agrees that this is a common phenomenon:
A certain assimilation normally takes
place in many forms of sentence, by
which the tense of their verbs is
changed to the past when they are made
into clauses dependent on another
sentence whose verb is past, even
though no notion of past time needs to
be introduced into the clause.
He mentions that the past tense is normal, but the present tense is also used in this type of sentence, to a somewhat more vivid effect.