We stock Perl Hide glue which is often used for the same purpose. Many of the old rocking horses were coated with gesso which is a batter made from mixing hide glue water and talc or calcium carbonate (chalk dust). This is used because it fills the grain and can be sanded to a brilliantly smooth surface, giving a fantastic base to build your painted finish on.
Rabbit skin glue is just a slightly inferior form of Perl Hide glue. It is often found in art supply shops and is used as a size for artists canvases.
Either glue will do the job. Click on the link below and then on the Perl Hide Glue link to view the info on our glue and Talc to see info about gesso.
U-Beaut Products
Hope this helps.
Cheers - Neil