It seems reasonable to invent the rouble sign symbol usable in LaTeX. The very existence of a special package for euro sign (eurosym) gives me hope that the moment when a full-blown package for rouble signe is created is not far off.

Tecnical note. The height of the bar must depend on the letter height, the length must depend on the letter width. However, it is for that purpose why TeX was invented. That’s why the horizontal position of the bar will be determined in em units (M letter width), and the vertical position of the bar will be determined in ex units (x letter height).

Let’s stick to common sense when creating the desired command. Here are some considerations and guidelines based on the existing rouble symbols:

1. The rouble sign consists of one Russian “R” glyph and a horizontal bar.
2. Assume that the bar is closer to the round cap than to the bottom.
3. Suppose that the bar’s left end is aligned with the serifs and its right end is aligned with the center of the thick arc where its tangent is vertical.
4. Let’s say that in the sans serif version the bottom of the arc is horizontally extended to the left at the serif width and so is the bar.
5. Put that six glyph styles will be enough: regular, bold (bf), italics (it), bold italics (bf+it), sans serif (sf) and bold sans serif (sf+bf).
6. The glyph metrics must be equal to that of the capital letter “Р”.
7. Coarse fool-proofing: the command should be style- and font-independent, but scalable. The style of the symbol must be explicitly selected by user.

\newcommand{\rouble}{{\rm{Р}\kern-.635em\rule[.5ex]{.52em}{.04em}\kern.11em}}
\newcommand{\roubleit}{{\it{Р}\kern-.54em\rule[.5ex]{.48em}{.04em}\kern.07em}}
\newcommand{\roublebf}{{\bf{Р}\kern-.64em\rule[.4ex]{.51em}{.05em}\kern.13em}}
\newcommand{\roublebi}{{\bf{\itshape{Р}\kern-.565em\rule[.4ex]{.48em}{.05em}\kern.08em}}}
\newcommand{\roublesf}{{\sf{Р}\kern-.635em\rule[.43ex]{.52em}{.05em}\kern-.52em\rule[.68ex]{.12em}{.05em}\kern.52em}}
\newcommand{\roublebs}{{\sf{\textbf{Р}\kern-1.6ex\rule[.35ex]{.58em}{.068em}\kern-.58em\rule[.65ex]{.15em}{.068em}\kern.57em}}}

The bold sans serif symbol is very buggy so I had to use the vertical unit of measure when moving the line horizontally. Here is the illustration of the final result; the frames allow us to make sure that the dimensions of the new symbol are equal to those of the original letter.

I would like to remind all the users that this code is a dirty hack, so let’s wait until monsieur Lvovskiy, staying true to his authenticism, created his own rouble sign package. Maybe this monsieur Kotelnikov will quest for the solution of this noble problem.