While using HEC-RAS 4.0 Beta, how to set PF1 in Steady Data Flow?
PF is the profile flow. The idea is that it represents the flow through the reach (designated in the geometry, which can be constructed in arc using GeoRAS) at a given time (e.g. time of peak flow). If you have done hydrologic modeling using HMS the flow values can be imported using the DSS file structure. The other common way to populate these flows is based on a gage or a model/function output based on gage data for the corresponding reach (row).
Once the steady flow data (top dialog box in question) is complete, the steady flow analysis is run from a separate dialog box (Run-Steady Flow Analysis).
Your going to need to have some of model geometry built before you can add flow. Your are in the correct dialog, so you would just key in the flow at a specific river sections (RS) or at multiple sections.
HEC-RAS usually has the option to install example projects (look under the Help menu). I would suggest installing these and taking a look at a few examples.
Also, HEC-RAS v4.1.0 has been out for some time now so you may want to check that out too. Sorry if you already know this.
Hope this was helpful.