Using Fonts with Rainmeter

[balala]

If you're using the said fonts for most of your skins, you could simply install those fonts in Windows and be done with it.

This might be a solution, however makes the skins hardly distributable. I mean that you can't do the skin installer to install the font(s) to Windows and a user most probably won't have all the needed fonts to can use them in skins.
I still think the "inefficient" solution is the best one possible. Finally those files of the fonts usually are not too huge and can be included into more @Resources folder.

[Yincognito]

This might be a solution, however makes the skins hardly distributable. I mean that you can't do the skin installer to install the font(s) to Windows and a user most probably won't have all the needed fonts to can use them in skins.

Hardly distributable is the accurate description, indeed. Not because it would be impossible for the skins and their fonts to be distributable (since fonts themselves are distributable / downloadable on their own regardless of skins, not to mention that despite the skin installer being unable to directly install fonts they can still be installable by the skin itself on its first run via some command line approach assuming they are already stored somewhere in the skin package), but because it would be quite inconvenient / uncomfortable to do so. You're right though, this solution is most likely undesirable, as most people would expect a single click and go one. I only included it to cover all angles / possibilities.

I still think the "inefficient" solution is the best one possible. Finally those files of the fonts usually are not too huge and can be included into more @Resources folder.

Although I can't stand duplicates and I perfectly understand the point made about them, I prefer the current system as well, just like you do. Fonts are generally meant to be skin specific in Rainmeter, collecting fonts is a Windows thing (which, by the way, doesn't happen only in the C:\Windows\Fonts folder, but also in the C:\Windows\WinSxS\amd64_microsoft-windows-font-... folders, in the C:\Users\[User]\AppData\Local\Microsoft\Windows\Fonts folder, maybe even others, if one wants to talk about inneficient solutions and duplicates). If Rainmeter would implement the common font location like with plugins, not only it would add tons of them there from previously installed skins, but considering that the font file names are usually different from font face names it would make getting rid of the unused or unwanted ones difficult (even with a PowerShell script that could identify their font face names). For this case though, I suspect that if the skins are own work and related to each other, including them in a skin suite would be suited and would solve the inneficiency as well.