zDimRadius detects the arc and fillet segments in the objects you pick and dimensions their radius. The label is always r=value.

Quick start

Run zDimRadius.
Pick curves or Brep edges.
The tool finds the parts that can be reduced to circular arcs and dimensions them.
Adjust the TEXT, DIMENSION and ARROW groups.
Mark commits the dimensions. Cancel discards them.

A row at the top has three presets, Tiny, Small and Large Object. The parameters are in three group boxes: TEXT, DIMENSION and ARROW.

TEXT

Unit Format: the length unit format of the radius text, from the same list of units as zDimLength.
Text Size: the height of the dimension text.
Decimal Places: the number of decimals in the value. All three presets share the same range.

DIMENSION

Label Offset: the distance from the arc to the label, along the radius direction.
Show Circle & Center Cross (on by default): draws a dashed full circle and a center cross for each arc, as a reference.

ARROW

Arrow Style / Arrow Size: the style and size of the leader arrow.

How the settings work together

Changing Unit Format regenerates every label text.

Input requirements

Only parts that can be reduced to a circular arc are dimensioned. Straight segments and free curves that are not arcs give no dimension. A mixed curve with fillet or arc transitions dimensions only its true arcs.

Good to know

If a picked curve changes its structure while the dialog is open (more than a move or a scale), a one-time notice appears saying the curve has changed and the dimensions may no longer be accurate, and suggesting you run the command again.
If you close the dialog without pressing Mark, the tool removes its empty layer, as zDimLength does.
After Mark, the dimensions are split into 3 separate groups: the text labels, the reference circles and cross lines, and the leaders. This lets you select or hide one group at a time.