unable to check signature after installing youtube-dl. 'public key not found' error

[kimbaudi]

Make sure you are using the latest version: run youtube-dl --version and ensure your version is 2016.07.03.1. If it's not read this FAQ entry and update. Issues with outdated version will be rejected.

• I've verified and I assure that I'm running youtube-dl 2016.07.03.1

Before submitting an issue make sure you have:

• At least skimmed through README and most notably FAQ and BUGS sections
• [x Searched the bugtracker for similar issues including closed ones

What is the purpose of your issue?

• Bug report (encountered problems with youtube-dl)
• Site support request (request for adding support for a new site)
• Feature request (request for a new functionality)
• Question
• Other

Description of your issue, suggested solution and other information

After successfully installing youtube-dl, I am unable to check the signature on my Ubuntu machine. I followed the instructions on https://rg3.github.io/youtube-dl/download.html

I installed using curl:

sudo curl -L https://yt-dl.org/downloads/2016.07.03.1/youtube-dl -o /usr/local/bin/youtube-dl
sudo chmod a+rx /usr/local/bin/youtube-dl

I tried to check the signature:

sudo wget https://yt-dl.org/downloads/2016.07.03.1/youtube-dl.sig -O youtube-dl.sig
gpg --verify youtube-dl.sig /usr/local/bin/youtube-dl
rm youtube-dl.sig

I get the following output:

gpg: Signature made Sun 03 Jul 2016 07:30:08 AM PDT using RSA key ID 18A9236D
gpg: Can't check signature: public key not found

How can I check the signature?

[yan12125]

See #9647

[YuvalZilber]

i have the same problem.
i saw #9647 and he gives a download for a .asc file.
what should i do with that?