How do I crochet a dickie for a v-neck jersey?

Hi Mary, maybe this link will help you...........

https://www.pinterest.com/loishill76/knit-dickey/

https://www.loveknitting.com/us/search-v2?q=dicky&p=4

Without seeing how the edges of the V-neck are finished it is a little hard to say, but as jersey is a knit, I am assuming the edges are somewhat stretchy, and that the V neck length is a little too long for you and you want to fill it in?

I would sew a trim with sturdy weight first on to the fabric edges of the V neck. If the holes are large enough for a crochet hook, then you will be able to use them to cast stitches on to and to continue crocheting in the V space.

If the trim that you are using is cotton, be sure to pre-shrink it first before sewing it on, otherwise it will likely shrink more than the jersey when the garment is washed, then will not lay flat.