Have you told your father not to kiss your neck? If you feel uncomfortable, then yes it is a problem. Because you have a right to feel safe and comfortable regardless of what others' intentions may or may not be.

First, you can tell the individual (father or anyone else who crosses a line) it's not okay.

Second, remind/mark the boundary one more time if necessary.

Third, if they continue to cross the line I would no longer spend time with them because they appear unwilling to respect your clearly marked boundaries.

My above three steps would not apply to criminal acts...those need to be reported to the police and safe distance is the immediate priority.