In 1966 the Ideal corporation released the first licensed Muppet toys. This page is from their trade catalog from that year promoting their new Muppet line for toy shops to buy.
The full ad shows Rowlf, Kermit and Snerf plush dolls and the packaging in which they would be sold.
While Rowlf and Kermit would go on to be huge stars, the Snerfs would be best remembered from their 1977 performance of " In a Little Spanish Town", from the Bruce Forsyth episode of The Muppet Show.
According to the Muppet Wiki, "there's no evidence that the Snerf puppet was actually manufactured and sold."