Most sculptors work with wire of some sort for the limbs, or the whole body, as it allows posing and reposing of an armature to get a believable pose. It would help avoid having the legs this straight for example, which are part of what make the pose of the figure so rigid (compare with the illustration - v. good natural bend to the knee). At this scale wire hangers are often used but twisted strands of thinner wire would work well too.
By the way, I would recommend always sculpting a head off the body and then attaching it to the armature; likely to yield a better result for nearly everyone compared to sculpting it in situ (especially if you ever do it tilted or at an angle). For much the same reason it's a good idea to sculpt a head bald, then add any beard, hair or headdress - just like why most of us sculpt a rough body first before adding clothing.
Einion