Hi,
Sorry coming late to this one.
As long as you have plenty of ink on the pins and give a good firm slap (not too excessive) then the tattoo will take. - As Robert says if the skin is punctured a bit of ink rubbed in will not do any harm, but its not strictly necessary.
Trials have been carried out on this ink by a VERY big slaughterhouse, for ink retention when slapping just before slaughter, a week before slaughter and 3 months before slaughter - all have passed the requirements - and this ink is in the process of being mandated by some of the larger supermarkets - so the ink is not a problem.
Sometimes the tattoo is not visible on the live animal but can be seen clearly on the carcass after slaughter and cleaning.
But if in doubt do it again, a little more forceful with PLENTY of ink on the pins - they are very sharp and should penetrate the skin easily
Thanks