I am exporting all the appointments using the RadScheduler's Export Calendar functionality (RadScheduler.ExportToICalendar(apptCollection, true)). 

I have the scheduler working with both regular and recurring appointments in my project with RadScheduler along with different timezone for each of the appointments within the scheduler properly. 

However, when I export the same through the above API as an ICS file, I am seeing that the date time is always coming out as UTC on recurring events giving me the wrong results in Outlook. 

Using the following setup, resize the appointment so that when releasing the mouse, it is over the appointment as demonstrated in the attached video with the attached project.

The RecurrenceRule does not have the correct Exceptions when modifying the series. The behavior in Outlook is to clear all exceptions when modifying the series. The behavior in Google Calendar is to consider the exception and modify the recurrence rule accordingly.

Create a recurrence appointment (starts on 20th Feb at 8:00 am, recurring daily), whose recurrence rule will be stored in the database as (Picture 1):

DTSTART:20180220T080000Z
DTEND:20180220T083000Z
RRULE:FREQ=DAILY;INTERVAL=1;BYDAY=MO,TU,WE,TH,FR,SA,SU

Further, I create an exception on 23rd Feb, which changes the start time to 8:15 am. This now, in Addition to inserting a new record for the exception, updates the master's recurrence rule to (Picture 2):

DTSTART:20180220T080000Z
DTEND:20180220T083000Z
RRULE:FREQ=DAILY;INTERVAL=1;BYDAY=MO,TU,WE,TH,FR,SA,SU
EXDATE:20180223T080000Z

So far, so good. Now I edit the master and change its start date to 19th Feb. I expect, that the master keeps the exception for 23rd, but the result is another one. The exception record is kept unchanged as expected! BUT the EXDATE in the master is wrong (Picture 3):

DTSTART:20180219T080000Z
DTEND:20180219T083000Z
RRULE:FREQ=DAILY;INTERVAL=1;BYDAY=MO,TU,WE,TH,FR,SA,SU
EXDATE:20180222T080000Z

https://www.screencast.com/t/OQyCn2jM

Reminders popup outside the page that the scheduler is used.
Because re-adding the same scheduler in many pages is very bandwidth consuming so what about creating a minified scheduler control for reminders so the user will be reminded in all pages about events.

When the timezone of the client is before UTC (e.g. UTC -1 or UTC -3) if you use the calendar for navigation, you will be navigated to the day before the selected one.

https://www.screencast.com/t/KlQtYDOxl

Workaround: 

var $ = $ || $telerik.$;
var $T = Telerik.Web.UI;
var $TS = $T.Scheduler,
$TSR = $TS.Rendering,
$DateTime = $TS.DateTime;
var $SB = Telerik.Web.StringBuilder,
timePerMinute = 60000,
timePerHour = timePerMinute * 60,
timePerDay = timePerHour * 24,
daysInWeek = 7,
roundedCornersHeight,
anchorDateFormat = "yyyy-MM-dd";

$TSVM = Telerik.Web.UI.Scheduler.Views.Month;
$TSVM.Model.prototype._createTimeSlot = function (rawIndex, startTime, element) {
    if (startTime.getHours() == 23) {
        startTime = $DateTime.add(startTime, 2 * timePerHour);
    }

    return new $TSVM.TimeSlot(rawIndex, startTime, element);
}

$TSVM.Model.prototype.getTimeSlotFromDomElement = function (domElement) {
    var rawIndex = this._getRawIndexFromDomElement(domElement),
                startTime = this._getTimeFromDomElement(domElement);
    if (startTime.getHours() == 23) {
        startTime = $DateTime.add(startTime, 2 * timePerHour);
    }

    return new $TSVM.TimeSlot(rawIndex, startTime, domElement);
}


Telerik.Web.UI.Scheduler.Rendering.MonthViewRenderer.prototype._updateColumnHeaders = function () {
    var renderer = this,
        dayHeaderDateFormat = this._model.get_dayHeaderDateFormat(),
        firstDayHeaderDateFormat = this._model.get_firstDayHeaderDateFormat(),
        currentMonth = renderer._owner.get_selectedDate().getMonth(),
        visibleRangeStart = renderer._model.get_visibleRangeStart();

    $.each(this._contentTables, function () {
        var dateLabels = $("td div.rsDateWrap div.rsDateBox a", this),
            dayStart = visibleRangeStart,
            weekDayIndex = 0,
            weekStart = new Date(dayStart.getTime());

        dateLabels.each(function () {
            var isFirstVisibleDateOfMonth =
                    $DateTime.subtract(dayStart, visibleRangeStart) == 0 &&
                    dayStart.getMonth() == currentMonth;
            var dateHeaderText;

            if (renderer._owner._renderMode == $T.RenderMode.Mobile) {
                dateHeaderText = dayStart.getDate().toString();
            }
            else if (dayStart.getDate() == 1 || isFirstVisibleDateOfMonth) {
                dateHeaderText = dayStart.localeFormat(firstDayHeaderDateFormat);
            } else {
                dateHeaderText = renderer._getFormattedDateText(dayStart, dayHeaderDateFormat);
            }

            this.href = "#" + dayStart.format(anchorDateFormat);
            this.innerHTML = dateHeaderText;
            this.title = dayStart.localeFormat(Sys.CultureInfo.CurrentCulture.dateTimeFormat.ShortDatePattern);

            var otherMonthCell = currentMonth != dayStart.getMonth(),
                dateWrapElement = this.parentNode.parentNode.parentNode;

            $(dateWrapElement).toggleClass('rsOtherMonth', otherMonthCell);

            if (weekDayIndex == renderer._weekLength - 1) {
                // Move to the next week, skipping invisible days.
                weekStart = $DateTime.add(weekStart, 7 * timePerDay);
                dayStart = new Date(weekStart.getTime());
                weekDayIndex = 0;
            } else {
                dayStart = $DateTime.add(dayStart, timePerDay);
                weekDayIndex++;
            }
            if (dayStart.getHours() == 23) {
                dayStart = $DateTime.add(dayStart, 2 * timePerHour);
            } else if (dayStart.getHours() == 1) {
                dayStart = $DateTime.add(dayStart, -timePerHour);
            }
            if (weekStart.getHours() == 23) {
                weekStart = $DateTime.add(weekStart, 2 * timePerHour);
            } else if (weekStart.getHours() == 1) {
                weekStart = $DateTime.add(dayStart, -timePerHour);
            }
            // Wrappers are cleared here to avoid second
            // traversal of the cells.
            renderer._clearExtraWraps(dateWrapElement);
        });
    });
}

The Button text initially shows "Never", even though the appointment has a different recurrence. https://www.screencast.com/t/55Rl1CSa7F7y

This doesn't work: apt.Description = DescriptionText.Text;

There is a display issue when using the agenda view - if there are fewer than 4 events displayed then clicking on the date range in the header shows a calendar which is clipped at the bottom. Presumably this is due to it being constrained by the height of the events area. This occurs even though there is plenty of height available to the control. Please see the attached screenshot which is taken from your demo site:
http://demos.telerik.com/aspnet-ajax/scheduler/examples/overview/defaultcs.aspx

Hello

It would be good to have the calendars grouped vertically and to have the time displayed horizontally. Please see attached screenshot

Regards
Peter