Inspired by Pr. Christopher Hall, I would like to point out a neglected rubric in Holy Baptism, the Altar Book, p. 366. It's number 9:
"While making the sign of the cross during the blessing after Baptism, olive oil may be used to symbolize the sealing with the Holy Spirit for salvation (Eph. 1:13-14). This oil may be applied with the thumb."
This rubric restores for us LCMS and LCC Lutherans the ancient practice of the chrism (which was still present in Luther's 1523 Order and in the 1529 Order of Olavus Petri). Boo, hiss, though, on the word "symbolize" in the rubric. Far better to say that it manifests, that is, it reveals and confesses.
We use the chrism with each Baptism at St. Paul's precisely to manifest and confess that Baptism's gift is not only remission of sins but the indwelling of the Holy Spirit.