I own several books on Ronald Reagan, including a copy of "Reagan In His Own Hand" and read it quite often. I also campaigned for Reagan three times, 76, 80 and 84. However, Reagan never claimed to be a libertarian, nor did he support the libertarian agenda, philosophy and ideology. Reagan was a moral conservative, a social conservative and a law and order conservative. Reagan based his life on a set of core conservative values.
Reagan gave one extensive interview on the subject of libertarianism. That was the 1975 interview to the libertarian publication, Reason magazine. Many libertarians here on FR have taken what Reagan said in that interview and offered an inaccurate portrayal of Reagan's political beliefs. Reagan was a loyal Republican and staunch conservative.