Skinner led the Sabres with a career-high 40 goals last season after being acquired from Carolina in August. He's tied for 13th among NHL players with 244 goals since joining the league in 2010-11 and fifth with 191 even-strength goals in that same span.
His 82 even-strength goals over the past three seasons rank fourth in the NHL, behind Connor McDavid (92), Auston Matthews (86) and Patrick Kane (84). Botterill said he still sees room for Skinner, 27, to develop, too.
"I think there's still opportunity for him to go beyond that," he said. "Hopefully with us having younger players that are going to continue to improve around him and having a stronger team around him will just allow him to have better goal totals.
"The way he goes about having a work ethic and going about trying to find different methods of keeping his body in shape, training in the off-season and then also being a student of the game and where to go on the ice, body position around the net, I still believe he's growing as a player for sure."
Skinner becomes the second-highest paid player on the Sabres, behind Jack Eichel. Botterill downplayed potential concerns over those two contracts possibly creating salary cap issues down the road, with another top-line forward set to hit restricted free agency next summer in Sam Reinhart.
"I think this contract just goes to show you when very good players want to stay here in Buffalo and be part of it, we're going to find a way to try to get it done," he said. "Our goal is to continue to try to develop our players within our system and we want to give them big contracts. We want them to develop and be players that are deserving of their big contracts."
"I feel very comfortable having some of our top players taking pieces of our salary cap up. People talk about some teams throughout the league having 'cap situations.' Well they have cap situations because they have excellent players on the roster. That's what we're trying to get to."
Botterill said he'll continue to look to add to the team's scoring depth in the offseason, be it through free agency or trades.
"What we've talked a lot about is continuing to try to add more scoring to our group, especially up front, and that's why getting Jeff signed was such a big deal for us," he said. "We want to focus on adding to that group, not replacing it. And that's what we've accomplished with signing up with Jeff.
"We certainly are excited about some of our young players going into different roles, but if we can find a way to add a little bit more depth instead of relying so much on Jeff, Sam and Jack, I think that's certainly one of our goals here is an organization."
