9 day old puppy, was small for litter (one of 2 100g lighter than others) other one has caught up, this one seems a bit floppy and her skin seems loose....Large litter(6 ) for toy breed, all ather pups have doubled birth weight, this one has dropped today, but she is the only one to have opened her eyes! Dam has 9 functoning teats and seems fine.....Should I give this one a dropper feed of puppy milk to perk her up? Or will this interfere with dams supply? (I am a breat feeding supporter/counsellor and would never recommmend topping up to a human, but am concerned!)

I would try for today to put this pup on the best teats every hour or so so you are sure she is getting more.  the floppiness and loose skin sounds like pup is getting dehydrated. 

Is she latching on and feeding effectively?  If not then I would supplement her just to get her stronger.  With all the others feeding from the bitch it should not unduly effect the milk supply.

How much weight has she gained since birth?

Thanks I've been putting her on each time I go past. She has gained 300g,  (born at 250g)but down 25g today from yesterday. I am so glad someone on hear said to weigh daily as I wouldn't have noticed this so early.

Well her gain until now seems fine over double her birth weight, so I would just make sure she gets on and check weight again.

Have you considered Nutri drops ?

How is she this morning?