Now please do not laugh! :o) I am new to genealogical DNA testing...but quite experienced using DNA to prove ancestry of alpacas. Why can you use DNA testing to prove a male father of an female but you cannot use it to prove a male father to a human female?
Sure you can. The human female got one of her x chromosomes from her father and fully half of all her autosomal dna.
All you need is a sample from both.