Also see Fig. 2.4, Note 6 in D1.5.
My A2.4 Figure 7 provides no info on weld size. I interpret Article 3.5, which refers to Fig 7, as being illustrative in depicting combined weld symbols without necessarily being anything more than that.
CG
A2.4 is a standard for welding, brazing, and NDT symbols. It does not address workmanship or design issues or the requirements that are address by a specific construction codes or standard. Examples of codes that would include design and workmanship requirements include; D1.1 Structural Welding Code/Steel, ASME B31.3 Process Piping, NAVSEA S9074-AR-GIB-010/278 (NAVSEA TP278), etc.
The size of the reinforcing fillet will be addressed by the particulars of the construction code. For instance, AWS D1.1-2000 addresses the size of the reinforcing fillet weld in paragraph 2.14.3. NAVSEA TP278 addresses it a little differently. The standard joint details for NAVSEA TP278 are contained in MIL-STD-22D. That standard has provisions for the maximum and minimum size of the reinforcing fillet weld.
Rarely, except for thin material, is the reinforcing fillet as large as the width of the weld of the bevel groove (in the case of a corner joint).
The size of the fillet weld would be listed to the left of the symbol for (i.e., the reinforcing fillet weld) when the symbol is specified as a "complex" welding symbol.
Hope this helps. I can't over emphsize the need to check the requirements of the applicable or elected welding standard. If an AWS welding code doesn't apply, you can possibly refer to one of the AWS welding standards (railroad equipment, rotating equipment, mill cranes, etc.) that may be applicable to your application.
Best regards - Al