point in abbreviations

[Wolfgang Engelmann]

In Latex a tilde (~) is used behind a point in an abbreviation such as Dr. Smith
or i.e. (alternative \space, but in this case line break is possible)
In Lyx I am not sure how to do it. If I write
Dr.Smith the distance is too small
Dr. Smith too large
With Dr.~Smith (~ in Tex, red) even larger.
Thanks for a hint