No, not necessarily, although if that's what you've got, it won't do any harm. Multi purpose potting compost is usually neutral, and Skimmias do okay in that - they like neutral to acid soil.

Thank you. I've got both composts. Do you think it would be good to have a mixture of the two ?

I've got an ordinary Skimmia and a Magic Marlot.

Yes, good idea, no reason why not.

Thank you, you've been a big help.